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When it comes to documentaries about art forgeries, nothing has yet to surpass F For Fake (1975), which required the combined efforts of starring Orson Welles, François Reichenbach, Oja Kodar and Gary Graver to chronicle the scams perpetuated by Elmyr de Hory and Clifford Irving. More recently, Sam Cullman, Jennifer Grausman and Mark Becker have profiled Mark A. Landis in Art and Craft, Arne Birkenstock has examined the works of Wolfgang Beltracchi in Beltracchi: The Art of Forgery (both 2014), and Jean-Luc Léon gained remarkable access to Guy Ribes for A Genuine Forger (2015). But, in The Key to Dalí, David Fernández seeks to turn the forgery documentary on its head by showing how biology teacher Bartolomeu Payeras (aka Tomeo L'Amo) spent 25 years and a considerable portion of his savings trying to convince the art establishment that the painting he had bought for 25,000 pesetas (approximately £132 in today's money) in a Girona antique shop in 1988 was a landmark of early Surrealism, `The Intrauterine Birth of Salvador Dalí'.

Having dyed his hair to look younger for a recreation of the day he found the painting while recovering from a shoulder operation, Tomeo L'Amo explains how he rushed to the local library to verify the canvas measuring 100 x 70cm that he had found behind a pile of mattresses and paid the asking price without a qualm. Brother-in-law Salvador Padrosa remembers everyone humouring L'Amo over his discovery, which was made all the more intriguing by a signature dedication that read: `To my beloved teacher on the day of his birth 27-IX-96.'

As he knew that Salvador Dalí had been born in 1904, L'Amo was puzzled by the date. But, when Dalí died on 23 January 1989 before he could approach him to authenticate the painting, lawyer Tomeo Amorós and neighbour Xisca Tous were convinced he would continue his research. Under the name Tomeu Payeras, he contacted art restorer Carmen Sandalinas, who discovered three layers of paint. She also found him Dalí's description of the painting and a neat piece of 3-D imaging takes us into the heart of the image, as an actor voices the artist's journey back into the womb to become an angel stripped of his glory.

Experts like Santos Toroella were dubious from the outset. But L'Amo continued to delve into Dalí's life to find clues to support his claim and he sent a package of documents to the Gala-Salvador Dalí Foundation in Figueres. The board decided to dismiss the picture without seeing it first hand and journalist Josep Playa, Dalí specialist Richard Mas, Sotheby's director Alexandra Schader and Joan Miró's grandson, Joan Punyet Miró, all consider such a brusque response to be curious, even though there was no official catalogue record of such a painting.

Disheartened by the Foundation's response, L'Amo wrapped up the canvas and stored it in his studio while he built an extension to his house. However, a neighbour challenged the legitimacy of his planning permission and he was forced to demolish the structure and was saddled with debts that took a toll on his health. Neighbour Francisco Forteza suggests it took considerable fortitude to bounce back from such a costly setback and we see L'Amo reproducing Dalí's famous stare in a mirror, as he confirms that he was deflected for a few years before his situation stabilised and he could return to proving his case.

He found references in two of Dalís books, Secret Life and Diary of a Genius, to his intrauterine experiences and an early work depicting an angel. Carmen Garrido, a former technical department director from El Prado. explains the importance of dating the materials used. So, in 2004, L'Amo recontacted Sandalinas and they agreed to get the work x-rayed and discovered that, of the four pigments found on the canvas, one was only made available in 1909. This contradicts the experts who insist the `96' reference was to the date the picture was painted and L'Amo felt he had taken a giant step forward.

He decided to contact Robert Descharnes, Dalí's private secretary, who had come to have the last say on certifying his works. As he didn't have direct access, he entrusted this mission to a friend with contacts in the art world. After years of silence, L'Amo found Descharnes's address from a document authenticating a Dalí drawing in his collection and he set off for Paris in 2012. Son Nicolas Descharnes recalls the meeting and admits that they were initially sceptical because of the date in the dedication. But there was enough about the picture to persuade him to accept its possible authenticity.

Following a brash insert showing a Sotheby's auction over Schader revealing that Dalís can now command huge sums. L'Amo began to explore Dalí's comment about becoming a mirror image of Salvador Galo Anselmo, the seven year-old brother who had died before his birth. He subtracted the seven years from Dalí's date of birth and added six weeks to find the date the embryo formed of `the Divine Dalí', a character that the artist created in 1921 as the antithesis of his earthly being.

L'Amo then consulted graphologist José Pedro Venzal, who has experience of working for Interpol. He used chromatic luminescence to date the dedication to the 1920s and not only detected the use of two kinds of black ink, but also found a spelling mistake consistent with Dalí's muddling of `b' and `v'. Nicolas Descharnes found the verdict encouraging. But Richard Mas sniffily accuses Venzal of speculating in an unbecomingly unprofessional manner.

Undaunted, L'Amo used numerology to suggest that Dalí was following the likes of Albrecht Dürer and Leonardo Da Vinci in hiding messages in symbols and numbers within his pictures. He points to the 1977 numerical reworking of Diego Velázquez's `Las Meninas' and Basilio Baltasar from the Fundación Santillana commends L'Amo for spotting the significance of the number seven in Dalí's painting, as it is the sum of the Dalí brothers' birthdays and also the number of the Divine Dalí. But Mas rejects the findings as nonsense and scoffs at the idea of a `Dalí Code'.

Needing to corral his ideas, L'Amo wrote a book and showed the manuscript to Baltasar, who suggested that Dalí had dedicated the painting to the Divine Dalí, who had been his teacher. He also realised that this sense of duality chimes in with the owner of the painting himself. When not being biology teacher Bartolomeu Payeras, he is Tomeu L'Amo, who creates across a range of disciplines and is something of an eccentric. We see him playing his self-devised sport of underwater rock carrying and being chased by little shredded paper creatures that seem to scurry along the patio when caught by the breeze. He also fronts his own band to perform a song about an occupied toilet at a party to celebrate the August full moon.

Nicolas attends the launch of the book in Palma de Mallorca and he meets with Vinzal and Sandalinas, as he wrestles with the responsibility of declaring his verdict on the painting's authenticity. Mas hopes he errs on the side of caution, although it's not hard to detect a degree of personal animosity towards L'Amo as a rank outsider. The launch goes well, but the Dalí Foundation fails to acknowledge receipt of a copy, as well as L'Amo's latest research notes. He is hurt by their indifference and it's not surprising to see Mas backing their decision, as he fires another shot across the bows of Nicolas Descharnes for not rejecting L'Amo's claims out of hand.

L'Amo reveals that he received an e-mail from a Dalí specialist informing him that he had reached P104 of his book and decided the painting was bogus. As a scientist taught to back up a thesis with evidence, L'Amo is dismayed by such shoddy methodology and Garrido also avers that an art historian has to do more than simply gainsay on gut instinct, which is what Mas admits to doing, as he has also chosen not to study the painting in any detail. However, he continues to urge caution from Nicolas, who goes curiously quiet while L'Amo has to sell a painting bequeathed by his late mother to buy a new car, as he has invested everything he has in the Dalí project.

While trying to boost the disappointing book sales with a television interview in Girona, L'Amo reveals that the back of the canvas contains a sketch of a young woman that is similar to the ones that Dalí used to do of his sister, Anna Maria. On returning from this expedition, he learns that Robert Deschernes has died and that any hopes he has of getting his support have gone. Miró and Mas suggests that few auction houses would accept a certificate issued solely by Nicolas and Mas can barely suppress a smile, as he knows this puts L'Amo in an impossible position.

But, a few months later, L'Amo is present at the Institute of Fine Arts in Paris for the press conference at which Nicolas Deschernes declares `The Intrauterine Birth' to be a genuine work by Salvador Dalí. We see Nicolas sign the certificate and present it to L'Amo with confidence that his father agreed with his conclusion. Back home, where L'Amo has kept the painting tucked away in his studio, he expresses his relief that his efforts have not been in vain. He also twinkles, as he acknowledges that many will want to know if he sold the painting or not. But that, he concludes, is another story.

Well told by David Fernández, this is a fascinating policier told from the viewpoint of a detective who is also the suspect in the minds of the experts he needs to convince. Both Bartolomeu Payeras and Tomeo L'Amo are compelling characters and the contrast between the empirical sagacity of the former and the instinctive showmanship of the latter makes the bet-hedging surrounding his venture so understandable. But Richard Mas allows his professional scepticism to spill over into a distasteful arrogance that not only makes him the pantomime villain of the piece, but which also does a disservice to the embattled concept of expertise in the Trumpist age.

Fernández keeps things simple by keeping L'Amo front and centre and weaving the talking heads around him. Enzo Nakamishi and Carlos Duque provide a tinkling score that adds a playful element to the quixotic crusade. All that's missing is a shot of Mas's face when he heard that his advice had been ignored.

Following on the heels of Jennifer Peedom's Mountain, Peter Bardehle and Sebastian Lindemann's A Symphony of Summits: The Alps From Above takes us on an aerial tour of the mountain range that stretches through eight European countries from France to Slovenia and is home to around 14 million people. Filmed entirely with a Cineflex camera mounted on a helicopter and narrated by Emily Clarke-Brandt, this blend of geology, history, geography and sociology needs the biggest screen you can find. But, awe-inspiringly stunning though the visuals are, this is also an informative travelogue that highlights the wide variety of Alpine professions and pastimes.

Formed by a shift in two tectonic plates, the Alps were transformed by Thomas Cook and the tourist trade some 150 years ago. Now, each year, the population triples during the skiing season and we see holiday-makers enjoying the delights of a resort in the Dolomites of the South Tyrol. Off-piste skiers risk life and limb on the Wildseeloder in Austria and a rescue helicopter is called in to airlift an individual who suffered a spectacular crash. As Clarke-Brandt reminds us, this may be a playground for the rich, but it's also a forbidding landscape that demands respect and uses gravity to upend those humans who treat it without due care.

Swooping over the Matterhorn in Switzerland and all 4808 metres of Mont Blanc in France, we are whisked along the Aletsch glacier. However, Clarke-Brandt announces that the biggest stretch of ice in the Alps is fast diminishing and that half of the 5000 glaciers left in the range will disappear within the next 20 years. This will impact on the amount of drinking water available for cities like Milan and Munich, which also rely on the power generated by Alpine water. Tourist spots like the Stubai Glacier resort in the Tyrol will also suffer, as the ice will never return once it has melted.

Much of the power in Austria and Switzerland comes from carbon neutral water sources. But reservoirs like Salza in Styria cause their own problems, as they cause rivers to dry up and threaten fish stocks, as they can no longer reach their breeding grounds. Another reservoir, the Reschensee in South Tyrol, was created artificially in 1950 at the expense of villages like Graun and Rechen. The tower of the latter's 14th-century church was left to rise above the surface and Clarke-Brandt perpetuates the myth that its bells can still be heard in the valley on stormy nights, even though the chimes were removed a week before the demolition of the church in July 1950.

Moving swiftly on past the 220m Verzasca dam where James Bond bungee jumped in Martin Campbell's GoldenEye (1995), we see herdsmen in the eastern Swiss canton of Grisons blasting their tiba horns across the verdant valleys, as cattle and sheep are driven to the high pastures where bees also thrive. A cable car carries milk churns down from the heights at Laufbichl Alpe in Allgovia, Germany, while helicopters carry concrete for a construction project at Grasjochalpe in Vorarlberg. A spectacular shot shows two engineers monitoring the smooth working of a cable car before the camera follows the 1000m route of the 80 year-old cable way on Mount Predigtstuhl in Bavaria. Another reveals how desolate Austria's highest ski resort on Pitztal Glacier looks out of season before we follow a mountain biker speeding down a slope at Planai in the Scladming region of Styria.

Although the discovery of Ötzi the iceman in the Ötztal Alps proves that the mountains were inhabited as 3400-3100 BCE, it wasn't until Roman times that routes like the one across Austria's highest peak, Grossglockner, were established. These paths were also used by soldiers and we fly over the tunnels at Monte Plana and the blasted mountainside of Col di Lana while learning about the gruelling battles fought between Italian and Austro-Hungarian troops. In all, 150,000 men perished in these encounters, but Clarke-Brandt points out that conflict often prompted progress, such as the construction of the first mountain railway route in Austria's Semmering Pass.

The Emperor Franz Josef was the first passenger on this service, which opened up the region, as villages were founded along the track. The most breathtaking scenic route, however, is the Bernina railway between St Moritz in Switzerland to Tirano in Italy. This boasts the highest railway crossing in Europe and the red carriages look majestic against the granite. Similarly, the snaking roads carved into the Stelvio Pass in Italy and the environs around Grossglockner represent remarkable engineering feats and there's no denying the beauty of the vintage cars glistening in the sun as they glide along the tarmac. The Europa Bridge over the Wipp valley is also magnificent. But Clarke-Brandt notes that the locals dislike the fumes the vehicles produce and installed a tollbooth to limit the traffic. She also laments the fact that the urban sprawl of Bolzano was allowed to ruin a beautiful valley before noting that only the rich can afford to live in places like Ticino on Lake Lugano and Ascona on Lake Maggiore.

Back in the great outdoors, the camera picks up a couple of white-water kayakers in Venter Ache. But water has eroded the limestone in the mountains near Ferlach on the Austrian border with Slovenia. We also see a peak in the Dolomites that has lost its core. Yet tectonic shifts mean that the Alps continue to grow by 1mm each year, which is precisely the amount they lose to wind and weather. However, erosion loosens rock formations and we see the damage caused by an avalanche in northern Italy. Humans are to blame for the scarring of the landscape around the Erzberg ore mine in Austria, however, and Clarke-Brandt blithely announces that the seams will be exhausted in 50 years, which is a shocking statistic given that mining has been taking place her for centuries.

A detour takes us to the canyon the Rhine has cut through the mountains at Ruinalta. However, the mighty river was tamed by the removal of its delta leading into Lake Constance and the camera picks out the line where cold mountain water meets the sun-warmed lake. In the southern foothills of Provence, a river has cut the 25km Gorges de Verdon and the camera half-heartedly joins a rafting crew on a rapid descent. The scene is more tranquil at the Linderlof Palace built by Ludwig II of Bavaria, who visited it regularly before being confined at Neuschwanstein. We also fly over Herrenchiemsee, his tribute to Versailles located in the Chiemsee, before sampling a selection of Alpine churches, such as the Cistercian Stams Abbey in the Tyrol and the Frauenchiemsee in Bavaria.

While many go to the monasteries on retreat, some prefer cruising on the Königssee and others opt to sample a beer at St Bartholomew's Church near Berchtesgaden. For youngsters, nothing beats the Area 47 water park in the Tyrol or the sports offered on Lake Lucerne. There's no rest for Alpine hill farmers, however, as they struggle to match the prices of their counterparts in the valleys. We see hay being made on a steep slope before we inspect the pine harvest being taken on Villander Alp in South Tyrol and the apples being gathered on the banks of the River Estsch in Italy. As hailstones can ruin the crop, cloudbursting planes fly from Greisdorf in Austria to keep storms at bay. These forbidding images are followed by nocturnal shots of the Alps, with the stars twinkling above them in vast skies that are largely free of light pollution.

The sunrises are equally glorious and we see a team of huskies training on a summer morning. Even fleeter of foot are the Alpine ibexes coming down to graze, while a sure grip is also vital for those climbing Via Ferrata Pisciadù or the Eiger. Clarke-Brandt speculates why people risk their lives for a few moments of bliss on a summit. But we are whisked off again to view Aussarraschoetz in South Tyrol, one of the many crucifixes atop Alpine peaks, where she wonders whether a greater perspective can be achieved from such a lofty vantage point. An aquiline point-of-view shot is cross-cut with footage of wingsuiters in Lauterbrunnen in Switzerland before winter returns and wildlife battles to survive while the snow seekers play.

While it couldn't be more visually entrancing, this remains a frustrating film. The commentary meanders between hard fact and flights of fancy, while Clarke-Brandt's enunciation is often irksomely indistinct. Moreover, the use of captions to identify places is infuriatingly intermittent. But Klaus Stuhl's photography is outstanding and credit should also be given to pilots Guido Baumann and Walter Rüscher for enabling him to get so close in one shot to an eagle on a promontory. Roland Possehl's editing is also solid, as are Thomas Knop's evocative sound design and a score by Rich J. Dickerson, Luigi Meroni and Clemens Winterhalter that keeps reminding you how fantastic this would look on an Imax screen.

There have been a number of thought-provoking documentaries on the world's food supply over the last decade or so. Among the best are Nikolaus Geyrhalter's Our Daily Bread, Erwin Wagenhofer's We Feed the World (both 2005), Robert Kenner's Food Inc. (2008) and Katja Gauriloff's Canned Dreams (2012). Activist Valentin Thurn has also explored the amount of food that gets thrown away in Taste the Waste (2011). But he returns with 10 Billion: What Will We Eat Tomorrow? to consider how the planet will cope with rising population figures that are due to hit the titular toll by 2050. 

As he tucks into a helping of insects at a Thai snack bar, Valentin Thurn reveals that farmers are already struggling to feed us all, as fertile arable land and water become increasingly scarce. He meets Liam Condon, the chair of Bayer CropScience, which is one of the 10 companies controlling the world's supply of seeds. It holds more seed patents that its rivals and Condon is convinced that genetically modified food is the only way to prevent a food war in around three decades time. Johann Botterman, who heads the research centre in Ghent, shows off strains of rice that can thrive in salt water. But, while he says the need to feed must outweigh the risk of disrupting nature, Thurn reveals that the hybrid seeds produced by the likes of Bayer cannot be reproduced by the farmer and, therefore, they become wholly dependent on a supplier who controls quantity and price.

Out in Balasore in India, however, the Bayer seeds fail to survive a flood, unlike local seeds that have come to adapt to adverse conditions. Navdanya seed bank boss Kusum Misra explains how science doesn't always have the answers. Thurn is impressed by their independence, but notes that the corporations dislike such enterprise, as they can't sell the farmers enough seed, insecticide and fertiliser. He goes to the Kali + Salz facility at Philippstahl in Germany to meet Dr Andreas Gransee. However, he is more intrigued by the 250m slag heap that towers over the potash mine and notes that it will remain here long after supplies are exhausted in 50 years time.

With the age of artificial fertiliser coming to an end, German farmer Felix zu Löwenstein from Gutshof Habitzheim in Otzberg opts for organic alternatives like green clover. But his yields are a quarter down on competitors using artificial fertilisers and Thurn wonders whether this would still be enough if humanity changed its eating habits. Over a hideous shot of a chicken being left to die in a blue plastic barrel after having its throat cut, he informs us that, while 40% of Indians are vegetarians, a growing number are becoming carnivorous. They are supplied by the likes of Suguna Chicken in Coimbatore, which operates along German battery farming lines and chair Bangaruswami Soundararajan is proud of how quickly the company has come to dominate the market on the subcontinent. We are shown rooms filled with eggs and chicks, which are ruthlessly culled before the healthy ones are forced to exist in vast hangars. They are not caged, but it's no sort of life and few will find the mechanised process by which they are plucked and gutted any more palatable.

Thurn points out that we would need the resources of three planets if everyone on Earth wanted to eat meat in Western quantities. He wonders if there are ways around the problem and goes to meet organic farmer Karl Schweisfurth at Herrmannsdorfer Landwerkstätten in Glonn. In addition to letting pigs and cows have the run of the land, he also breeds chickens to lay eggs while they are being fattened for meat. As Thurn points out, this is rarely done any longer and he finds this disappointing, as it makes solid agricultural sense. However, the meat is more expensive at a time when there is a mass demand for cheap cuts and this means a greater need for animal feed.

Rei do Agro is a soy farm that has been established to supply the poultry industry by Jes Tarp at Ruace in Mozambique. He boasts that his fields are job producing factories, but he rants at his workers like a plantation owner of old and Thurn is right to question such management styles as antiquated. But, what bothers him as much is the fact that over a third of the annual grain harvest is fed to animals when humans are starving. He credits Tarp with reclaiming jungle for his farms when big companies take over smallholdings where it suits them. Katerina Alberto lost out when the nearby Hoyo Hoyo soy farm opened and she was unable to prove ownership of her plot because there was no register. Thurn worries that peasants losing out in such land grabs will migrate to the cities and be exploited and marginalised.

Bernd Schmidt's organic dairy farm at Hanfer Hof in Hennef uses grass from its own pastures to feed the herd. But its yields are lower and costlier than the market will bear and, as we see a montage of the various people we have met on Thurn's journey so far, he wonders if science can do something to relieve the strain on the land and our precious water resources. He ventures to the premises of Plant Factory Spread Inc. in Kyoto, where lettuce is grown in factory conditions under the watchful eyes of Haruhiko Murase from the University of Osaka, Toyoki Kozai from the University of Chiba and company chief Shinji Inana.

Next stop is AquaBounty on Prince Edward Island in Canada, where Ronald Stotish breeds genetically modified salmon in vast tanks. Dawn Runighan runs the farm and she shows how the addition of a single growth gene changes the size of sibling salmon. But, while Stotish insists he is making a major contribution to food security and will be hailed by history, Thurn notes that salmon are carnivorous and such facilities will need vast quantities of fishmeal to thrive. So, he rules out such intensive farming as a solution to feeding an expanding population.

He calls in on the Cultured Beef Project being run by Mark Post at the University of Maastricht. The professor explains how he uses stem cells from a cow to grow others in the lab and, thus, cuts down on the food required to fatten the animal and the methane it produces during its lifetime. He burns a burger costing €250,000, but reassures Thurn that the price will quickly come down and that consumers will prefer this eco variation when given the choice in their supermarkets. But Thurn dismisses Post's optimism that he is on the way to solving the world's food problem, as he avers that factory products will always be too expensive for the poorest people.

In order to gain an understanding of how the market works, Thurn goes to the CBOT food trading exchange in Chicago to see hedge fund manager Jim Rogers, who has transformed commodity dealing in foodstuffs. He says prices need to rise to keep farmers motivated and attract investment in the industry. But aid agencies blame the 2008 and 2011 grain price hikes on speculation and state that the avaricious should not be allowed to gamble with people's lives. Rogers accuses Thurn of being too dim to understand the basis laws of economics. But he retains his belief that financiers are profiteering off the labours of impoverished farmers who never see a penny of the windfalls.

An alternative form of trading has been devised by Rob Hopkins, who launched the Transition Town Network in Totnes in Devon. He has circulated `Totnes Pounds', which can only be used in local stores and ensure that money invested in the local economy circulates and brings benefits before it is hived off by outside concerns. Hopkins deplores that fact that the bulk of the town's £30 million food bill goes to two supermarkets and he is certain that the balance can be restored by people patronising local business selling homegrown produce.

Thurn takes Hopkins's lesson that intensive farming by hand on small plots is more productive and cost effective than mechanised farming in vast fields. He suggests this is the way forward for the developing world farmers like Fanny Nanjiwa from Mulanje in Malawi. She is fiercely proud of her independence and notes that the fluctuations on the global markets don't effect her, as she is always producing enough for her community at prices they can afford. Thurn is impressed by the quality of the food and the common sense of her approach. But, while he claims Big Agriculture could learn much from small operators like these, they are too locked into their ruinous profit-raking policies to bring about a change that could prevent shortages and starvation.

Rather than simply highlighting issues, Thurn comes up with some strategies to combat them. He suggests a boycott of meat from battery farms to reduce the number of soy plantations taking land away from indigenous smallholders. Another solution would be to buy organic, seasonal or local produce and to set up urban gardens like the Growing Power project that ex-NBA basketball star Will Allen founded in Milwaukee to allow people from poor neighbourhoods to grow and afford healthy food. This would also reduce the carbon footprint of much food shipping, while pioneering aquaponic greenhouses help keep down harmful chemicals and promote the growth of crops and the rearing of fish stocks.

In order to wrest power back from the agri conglomerates and the supermarket chains, community supported agriculture schemes are rising up around the world. We see a group under Hilke Deinet at work on the outskirts of Bonn in Germany and another in Todmorden in Yorkshire, where Mary Clear has established Incredible Edible to use neglected spaces in car parks, railway concourses and traffic islands to grow food. The UK only produces 60% of the food it needs and it wouldn't take much for supplies to break down. Thurn concludes by recommending a small-scale approach of local production to wrestle back control and keep people fed. But he places the onus on consumers to make the informed choices that can make all the difference.

This is very much a film of two halves, as Thurn visits projects driven by science and sense. Many of those shown in the first part of his journey are backed by large companies driven as much by profit as philanthropy. Some of the ideas are bold and imaginative, but he questions their efficacy and their ethicality in championing the individual over the institution. The schemes outlined in the second segment are mostly community led and offer people the chance to stake a claim in their future. Thurn is evidently more enthusiastic about these local initiatives and cuts them more slack in his analysis without quite going so far as to romanticise them. But he is right to conclude that change will only begin with people rethinking about what they put in their shopping baskets and making responsible choices when it comes to satisfying appetites or adopting sustainability.

Finally, opening with a quote from Friedrich Nietzsche about the perils of dealing with monsters, Barbara Eder's Profilers: Gaze into the Abyss provides a disconcerting insight into the methods of six men and women who spend their days attempting to fathom the psyches of serial killers and rapists. Based in Helsinki, Helinä Hakkänen-Nyholm is asked by a taxi driver whether she is anything like Clarice Starling, the character played by Jodie Foster in Jonathan Demme's The Silence of the Lambs (1991). She quickly distances herself from the film and insists that reality is very different.

Hoping to get a lead on a murderer who has stabbed a female factory worker some 20 times around the face, Hakkänen-Nyholm calls colleague Gérard N. Labuschagne in Pretoria. He suggests that a frenzied facial attack is usually carried out by someone who knows the victim quite well. Heading out into the veld in a thunder storm, he uncovers the skeletons of two children aged between 8-10 and hopes that forensics can establish how long they have been there. Since joining the force in 2009, Labuschagne has dealt with some 200 cases, 80 of which were murders. He claims you need a strong nerve and stomach to handle the pressures, as you see and smell so many unpleasant things that the job will soon find you out.

In Chicago, forensic psychiatrist Helen Morrison is trying to secure gubernatorial permission to carry out some tests on a recently convicted serial killer in order to prevent future cases. Her teenage sons watch her being interview on CNN and their dinner table conversation turns on notorious killer John Wayne Gacy's efforts to track Morrison down in the days before Google. Meanwhile, in Virginia, retired FBI profilers Roger L. Depue and Robert R. Hazelwood watch The Silence of the Lambs and Depue reveals that novelist Thomas Harris based Jack Crawford (Scott Glenn) on him.

On a train from Düsseldorf to Berlin, Stephan Harbort dictates details of a horrific crime that unsettle the female passenger sitting behind him. He is puzzled why a serial killer decided to tell his intended victim crucial details about himself and then let her go. Arriving in Berlin, he traces the steps of a woman who was raped in the elevator at the Europa-Centre and the sound of his dispassionate dictaphone delivery over footage of him revisiting the crime scene is decidely unsettling.

In Finland, Hakkänen-Nyholm helps a victim of abuse learn a safe place technique to enable her to cope with the trauma of her experience. She goes fishing on an idyllic island with her husband, who baits the hooks while she tells him about psychotic schizophrenics attacking the eyes of paintings because they find reading facial expressions so difficult. As she strokes her dog on the water's edge, Hakkänen-Nyholm concedes that she struggled to sleep while investigating her first capital case and it's clear that she still finds it difficult to avoid taking her work home with her.

Depue and Hazelwood have set up Academy Group, Inc. to offer profiling for private clients. They are hired by the father of a boy who is suspected of bludgeoning his 15 year-old girlfriend with a golf club that was later thrust through the victim's neck. As they discuss the evidence, they come to the conclusion that the culprit may well be the suspect's brother, who has admitted spying on the girl from a tree overlooking her bedroom window. The conversation and Depue's re-enactment feel more than a little rehearsed, especially as Hazelwood reaches his conclusion so swiftly. But Elder still captures the graphic nature of the information they have to consider and the extent to which they draw on their own experience of human nature and behaviour in making their call.

Sequences follow in which Hazelwood gives tips for women on how to remain safe from predators and Labuschagne tells a class of students about a case involving a couple who killed their victim in a graveyard and took various body parts home as trophies. One woman leaves after he shows them a slide of the man's skinned white face and explains how the female killer had written poems about the thrill of committing such hideous acts. Elder is allowed to film the perpetrators in court, as Labuschagne delivers his findings and we later see him reading a newspaper report on their sentencing.

In Düsseldorf, Harbort has dinner with his wife and confides that he doesn't know whether Guenther the waiter is telling him the truth or playing games about his mindset during the encounter that led to his arrest. Frau Harbort kisses the children goodnight, while her husband listens to tapes of a killer discussing his crimes. Further north, the action turns into a poor parody of a Nordic Noir movie, as Hakkänen-Nyholm muses on the motives for the murder while her husband guts a fish. She continues her deliberation in their sauna before they stand in the doorway at sunset and he puts an arm around her as they gaze into the distance.

Morrison is becoming frustrated in her efforts to implant electrodes in the brain of her serial killer and her neurosurgeon husband admits that he would have misgivings about such a procedure as it comes perilously close to human experimentation. She is convinced that environment and past trauma are less significant in determining a killer's behaviour than brain abnormality and she shows her younger son slices of brain matter on her kitchen worktop. But this particular specimen did nothing to advance the theories that she espouses on a radio chat show. However, she does find a surgeon who has been working on a range of psychological disorders and Morrison hopes that she will eventually be able to identify the serial killer gene.

At the Correctional Forensic Psychiatry unit at Lippstadt, Harbort goes to interview a killer called Klaus Dieter about what drove him to kill a woman he met on a dark country road. He recalls hearing her heels coming towards him and self-deprecatingly admits that the sexual aspects of the assault didn't last long before he strangled her. When Harbort asks how he knew she was dead, he replies with a smile that he has television and had seen what a corpse looked like in a murder show. Pressed about his fantasy woman, Klaus Dieter shrugs and says he is turned on by the thought of being satisfied and then killing his victim. Harbort seems to be struggling with his lack of remorse and matter-of-fact attitude to his crimes and sits alone at a bus stop outside the perimeter fence with his shoulders hunched.

While her husband bobs about in a boat on the sea, Hakkänen-Nyholm calls headquarters to deliver her verdict on the eye-stabbing case. She believes it was a robbery that went wrong and that the killer decided to mutilate the corpse as an act of punishment. Sitting on the shore, she reminds us that these cases make the headlines, but they always involve real people and this always makes them tragic. Later, she attends the Vappu Spring Festival and she looks around the revellers as if trying to fathom who among them has the makings of a rapist or a murderer. She wonders whether she would be happier if she had a different job, but isn't sure she would.

A deeply religious man, Depue believes that reaching out to the young can turn them away from violent crime and we see him playing basketball in a school playground. However, Morrison is certain that killers are born rather than made and she admits that she finds interviewing them gruelling work, as they are forever trying to play mind games to unsettle her. She checks into motels after such encounters to avoid bringing negative feelings into the family home and the sight of her sitting alone in a dimly lit room is tellingly contrasted with images of Labuschagne watching CCTV footage of a gruesome killing or standing in scrubs at a forensic mortuary, where cadavers are wheeled to waiting ambulances on gurneys that have to be hosed down to remove the blood and bodily detritus.

Such casually garish details confirm the unflinching nature of a film that almost feels confrontational in its determination to coerce the audience into looking through the eyes of Elder's six profilers. She is careful to avoid the suggestion that these individuals enjoy their job, but they clearly derive a good deal of satisfaction from using their skills to catch and prosecute killers and protect their communities from future crimes. They are all keen to highlight the special characteristics that enable them to keep gazing into the abyss without being dragged in themselves. But Elder spends too little time with each profiler to build up more than a superficial snapshot of their personality and their workload. Moreover, her depictions of them on a case or mulling things over during their leisure time are too stage-managed to allow any disarming spontaneity into proceedings.