There are several decent releases on offer this week, but the highlight is a 68 year-old piece of wartime propaganda that proved crucial in the evolution of the British docudramatic tradition. Adapted by John Dighton, Angus MacPhail and Diana Morgan from the Graham Greene short story, `The Lieutenant Died Last', Alberto Cavalcanti's Went the Day Well? (1942) brought a shocking new realism to screen warnings about the threat posed by Fifth Columnists to the Home Front. Moreover, it demonstrated the efficacy of authentic action and its greater suitability to cinema than the polished theatricality that had long been the hallmark of the UK film industry.

The story opens reassuringly, with verger Mervyn Johns explaining why there are so many German graves in the churchyard of the sleepy English village of Bramley End. However, things could easily have turned out very differently on that May Saturday in 1942 had it not been for the pluck and resourcefulness of the residents.

When Basil Sydney arrives at the head of a convoy of army trucks, he explains that he has been sent to review area defences and requires lodgings for 60 men. Vicar C.V. France and daughter Valerie Taylor offer the major the spare room and suggest that his troops occupy the village hall. But it soon becomes clear that Sydney is a German officer and that squire Leslie Banks, who is a corporal in the Home Guard, is a quisling under orders to facilitate an invasion.

The villagers remain blissfully unaware of the truth, however, and dismiss both postmistress Muriel George's misgivings at seeing one of the soldiers scold a scampish child and Taylor's concern that the newcomers use continental numerals when keeping score at cards. They even fail to react when rascally Harry Fowler finds some German chocolate in Sydney's luggage, as Banks convinces Taylor that it's probably just a test of their vigilance.

Realising he has to act while the Home Guard is away on manoeuvres, Sydney rounds up the locals in the church and France is shot for attempting to use the bells to send an SOS. Convinced nobody has heard the peal, Land Girls Elizabeth Allan and Thora Hird try to smuggle out a message on an egg. But it gets smashed when the delivery boy is knocked off his bike and the note that Marie Lohr passes to visiting cousin Hilda Bayley to fetch help after the returning Home Guard is gunned down winds up being jammed in a rattling window. Even George's effort to raise the alarm after slaughtering one of the Germans with an axe fails, as the telephonist at the exchange is busy gossiping and George is bayoneted before she can get through.

All looks lost. But Fowler and poacher Edward Rigby mount a rearguard that sparks resistance within the church. However, many will make the ultimate sacrifice before the counterattack succeeds.

At a time when most British pictures were designed to boost morale and stress the capacity of Allied forces to turn the tide of the conflict, Ealing Studios adopted a more realistic stance. Following Thorold Dickinson's The Next of Kin (1942), this brutally graphic drama sought to convey the ruthlessness of the enemy and the need to abandon traditional notions of fair play if it was to be vanquished. Little of Greene's tale remains, as the scenarists shifted the emphasis away from the poacher's selfless heroism and on to communal cohesion and the hideous difficulty of killing to survive.

The black comedic failure of the villagers to summon assistance is cleverly used to show the futility of any tactic other than meeting force with force and the sight of matriarchs and spinsters resorting to violence to protect their homes must have sent shockwaves through contemporary audiences. The casting of the usually noble Leslie Banks as a traitor would have had a similar effect. But such iconoclasm would remain a feature of Ealing's output, with even its justly famous whimsical comedies having an anti-establishment edge designed to discomfit the complacent middle-classes.

Collaboration of a very different kind comes under scrutiny in Rachid Bouchareb's London River. However, this well-meaning drama is so hamstrung by rigid political correctness that it ends up saying much less about racial tension in modern Britain than it clearly intends. Set in the immediate aftermath of the 7/7 bombings in 2005, the storyline is so dependent upon simplistic stereotypes and blatant counterpoints that it feels more TV-movieish than one would expect of a director whose last outing, Days of Glory (2006), recreated so sensitively the experiences of France's Maghrebi soldiers during the Second World War.

Falklands War widow Brenda Blethyn has a smallholding on the Channel sland of Guernsey and while she is in the local church listening to a sermon about loving one's neighbour, Malian migrant Sotigui Kouyaté is praying towards Mecca in the Provençal olive grove where he works. However, they each set off to London upon hearing news of the attacks on the Underground and the No.30 bus, as Blethyn can't reach her student daughter Jane on the phone and Kouyaté's estranged wife is concerned that she has not hear from their son Ali in weeks.

Disconcerted by the multiculturalism of Jane's North London neighbourhood, Blethyn is given permission to stay in her flat by shopkeeping landlord Roschdy Zem. However, with the police proving almost indifferent to her fate amidst the carnage and chaos of the atrocities, the increasingly desperate Blethyn is reduced to posting Jane's photo on a noticeboard near the tube station in the hope that someone can provide her with some information. Lodging in a hotel he can barely afford and being assisted solely by imam Sami Bouajila, Kouyaté recognises Ali from the picture. But when he contacts Blethyn, she is so appalled by the prospect that her child has not only been learning Arabic, but might also have been dating a potential Muslim terrorist that she has Kouyaté arrested.

Deeply ashamed of her actions, but still finding it difficult to suppress her parochial bigotry, Blethyn offers Kouyaté use of the sofa and they work together to ascertain that Ali and Jane were in love and had booked tickets for the Eurostar on the morning of 7 July. Relieved by the thought that their offspring are almost certainly safe in Paris, the pair finally take the time to get to know each other. But they have one more dreadful discovery to make.

Saddling its willing stars with some incredibly clumsy dialogue, this is a film that frequently feels lost in translation. Seemingly insufficiently versed in either English idiom or the rhythms of London life, Bouchareb pushes coincidence to the limits of contrivance and while Kouyaté (who, sadly, died in April) is allowed to adopt a sagacious dignity, Blethyn is coerced into exhibiting knee-jerk caricaturistics that over-emphasise the couple's already evident cultural and philosophical differences. Armand Amar's jazzy score similarly strikes a discordant note, although Jerôme Almeras's handheld camerawork ably conveys the intimacy and anxiety of the harrowing situation. More successful as an insight into how little parents know about their children than a tract on the perniciousness of prejudice, this still paints a depressing picture of a society riven less by hatred than by the inability and unwillingness of its diverse ethnic groups to communicate.

The capital also provides the setting for Brad Watson's The 7th Dimension, a supernatural twist on the cyber conspiracy thriller that appeared in a handful of festivals under the title Beacon 77. Despite containing several implausible plot points, this is an ambitiously complex venture into Da Vinci Code territory that is played with laudable intensity by a cast largely drawn from television drama.

When best friend Lucy Evans heads to a creepy apartment block to confront classmate David Horton about the state of their relationship, student Kelly Adams insists on accompanying her. Once inside, however, she discovers that Horton is assisting wheelchair-bound hacktivist Jonathan Rhodes and girlfriend Calita Rainford in a bid to break into the Vatican's online archive in order to crack the code hidden in the Torah.

Zipping around a cramped room made all the more claustrophobic by the banks of computer screens, Rhodes explains that he intends unlocking the secrets of existence to pass through its different dimensions and attain god-like wisdom and power. And there's no going back for either Adams or Evans, when the former just happens to know the passage from the Book of Daniel that breaches the papal security system and the latter begins deflecting the thoughts of the psychic spies detailed by the Pentagon to sabotage Rhodes's activities.

Shrewdly using the ranting Rhodes as their mouthpiece, Watson and co-writer Debbie Moon make few compromises in discussing such weighty issues as religion, technology, intellectual responsibility, fate, the future and the mysteries of life, the universe and everything. But they push their luck in bestowing the resolutely ordinary Adams with the mental alacrity to challenge Rhodes's grandiose schemes. Moreover, they also struggle to make the viewer care very much about either Evans's crush on Horton or the devoted Rainford's sense of betrayal as Rhodes gets ever closer to his goal.

Nevertheless, Watson makes moody use of his setting and his editing of Tim Wooster's restless imagery is disconcertingly slick. He's also coaxes a fine performance out of Rhodes, although his rapid delivery and descent into smug derangement serve to expose the limitations of his co-stars. Yet, for all Watson's aspiration and ingenuity, this succumbs to the convolution and verbosity that has condemned cyber punk to being a misfiring sub-genre.

Even before the World Cup has reached its climax, the image of a smiling South Africa that the media has worked so hard to convey is quickly quashed by the harsher realities of life in the Rainbow Nation depicted in Ralph Ziman's Gangster's Paradise: Jerusalema.

Having paid his dues as a juvenile carjacker for Russian-trained, ex-ANC guerilla Jeffrey Sekele, Rapulana Seiphemo concludes that Soweto is too small a place for his over-vaunting ambition and he sets himself up as a real-estate crime boss in the Hillbrow district of Johannesburg. Taking Karl Marx, Dale Carnegie and Al Capone as his role models, he adopts the mantra `Steal big and hope like hell you get away with it', and has soon made enough lucre to attract the attention of wealth Jewish girl Shelly Meskin, as well as earn the enmity of Nigerian drug baron Malusi Skenjana and Afrikaaner cop, Robert Hobbs. Even his relationship with childhood buddy Ronnie Nyakale changes, as Seiphemo's bid to stay on top of the world sets him ever more firmly on the road to ruin.

Sticking closely to the generic formula forged in the classic Cagney-Robinson era of the 1930s and given more political trenchancy by such Developing World variations as Mapantsula and City of God, this is a dismaying portrait of South Africa in the decade following the collapse of apartheid. Ziman ably captures the sense of unleashed optimism during the `affirmative repossession' phase of Seiphemo and Nyakale's career (when they are spiritedly played by Jafta Mamabolo and Motlatsi Mahloko), but the socio-economic authenticity slips as the proceeds of the Hillbrow People's Housing Trust cause Seiphemo to lose touch with reality. Nevertheless, this unflinchingly exposes the extent to which racism continued to shape daily life under both Nelson Mandela and Thabo Mbeki.

Doctor's wife Kristin Scott Thomas gets to sample life in the lower depths when she falls for illegal Spanish worker Sergi López in Catherine Corsini's Leaving. Echoes of Madame Bovary and Lady Chatterly's Lover reverberate throughout this brooding drama, which has little new to say about the cross-class romance. Yet, while it may not rank alongside Claude Chabrol's dissections of bourgeois morality, it is certainly credible and disconcerting.

Having devoted 15 years to brusque husband Yvan Attal and their children, Alexandre Vidal and Daisy Broom, Nîmes housewife Scott Thomas is preparing to return to work as a physiotherapist. Attal has agreed to convert an outhouse into an office and builder Bernard Blancan decides to cut a few corners by sub-contracting the job to López. Intrigued by his rough charm, Scott Thomas helps López dispose of the junk cluttering the room and offers to drive him across the border to visit daughter Berta Esquirol after he breaks his ankle trying to stop her runaway car.

Over dinner, Scott Thomas recalls her time as an English au pair and López sings her a Catalan song. But he mistakes her fascination for a come-on and they return to France in silence after he tries to kiss her in the street. However, with López no longer around every day, Scott Thomas begins to miss him and a trip to his apartment in a rundown part of town sparks their affair. Unable to control her emotions, she informs Attal she wants a divorce. But he is determined to make her suffer so much that she will return to his idea of domestic bliss. Consequently, the lovers only get to spend a few idyllic days in the Provençal hills before Attal begins using his contacts to sabotage their relationship.

Struggling to cap the gunshot with which the action commences, Corsini uses Agnès Godard's restless handheld imagery to force the audience to share in every aspect of Scott Thomas's amour fou. Love-making scenes are depicted with a gasping intensity that contrasts with the backbreaking manual labour that the pair has to undertake on a fruit farm after Attal cuts off his errant wife's finances. A sequence at a service station, as Scott Thomas tries to sell her watch to pay for petrol, is also excruciating. But the burglary of her own home that results in López's arrest feels contrived, as does the division of loyalty between Vidal and Broom.

Scott Thomas, however, remains utterly believable throughout, with her eyes betraying the pain of entrapment, the fleeting ecstasy of being desired again and the steely determination to stand by her man. López also does a decent job of displaying awkward macho affection, while Attal is hissably conniving and vengeful. But Corsini has few original insights to offer into the debasement women endure in either domestic hell or adulterous guilt and not even the Georges Delerue and Antoine Duhamel refrains borrowed from classic François Truffaut films can raise this above arthouse soap.

No such glib term could be applied to Ronald Bronstein's Frownland, which is one of the most unique pieces of American cinema in decades. But while outsider cinema may have a new anti-hero, few are going to identify with the needy, incoherent, self-loathing loser played by Dore Mann in this savage study of urban alienation and the slow death of communication.

With Mann speaking endlessly, but saying little, this could be dubbed ramblecore. However, the shabby Brooklyn charity worker's anger and confusion become more understandable in view of the bitter depiction of whining, self-harming girlfriend Mary Wall, duplicitous wannabe boho roommate Paul Grimstand and snootily indifferent buddy David Sandholm. With Bronstein refusing to impose order upon Mann's haphazard existence and Sean Williams shooting in intrusive close-up, this is indie cinema on the edge of insight and ennui, and its unrelenting insistence will either intrigue or infuriate.

Mann's inarticulacy is evident from the moment he struggles to find words of solace for a sobbing Wall, after she bursts into his cramped room in the dead of night. Indeed, a combination of his stammering ministrations, a woeful attempt at sock puppetry and a down pillow bring Wall out in hives and she exacts her revenge by scratching the paintwork with a push-pin that she then stabs into Mann's forearm. She leaves in sulky silence next morning and Mann has to endure the usual ignominious ride to work in the back of hard-nosed Carmine Marino's van, with chugger colleagues who barely acknowledge his existence.

The people he meets on suburban doorsteps in a bid to raise funds for a multiple sclerosis charity are no better disposed towards him. However, they're not as openly hostile as either Grimstand's inept experimental musician - who sneers at Mann when he asks him to pay the electricity bill and then steals his candles when they're cut off - or Sandholm's reluctant friend, who fast forwards through a Buster Keaton comedy when Mann dozes off on his sofa to speed up his departure.

Yet, just as he's established Mann's excruciating routine, Bronstein abandons him to follow Grimstand's desperate bid to coax the parents he detests into lending him some money and his sorry attempts to find a job. However, a lengthy sequence in which he takes an IQ test and then kvetches about it with fellow applicant Paul Grant proves a digression too far and it's almost a relief to return to the near-hysterical Mann, as he schemes to find a replacement lodger and gets into a fight with Sandholm when he tries to sneak into his apartment block.

The concluding segment - in which Mann staggers into a nightclub with a bleeding ear, only to be mocked by the trendy patrons and forcibly ejected - epitomises his tragicomic misfittedness. Yet, even the sight of this pathetic loser hitting rock bottom can't quite elicit our sympathy. It's doubtless this difficulty in knowing exactly how to take this picture that delayed its UK release by three years. But Mann's performance is quite remarkable, with its squirming intensity surpassing anything that has been nominated for an Oscar in the interim and enabling Bronstein to take indie exploitation into lower depths that others will hopefully have the courage to explore.

Finally, there's a touch of contentious nostalgia in When You're Strange, Tom DiCillo's documentary about The Doors. Making splendid use of archive material, including clips from the unfinished underground film HWY: An American Pastoral, this is a slickly assembled tribute that is narrated with typically laid-back aplomb by Johnny Depp. But, while DiCillo charts the combo's changing fortunes between 1965-71, he singularly fails to explain why singer Jim Morrison went from being a shrinking violet who would often perform with his back to the audience to a wannabe Rimbaud, whose antics enraged the establishment, delighted the fans and bemused his helpless bandmates.

The son of an admiral who saw action in Vietnam, Morrison renounced his family on quitting the UCLA film school to form a group with keyboard-playing classmate Ray Manzarek, jazz drummer John Densmore and guitarist Robby Krieger, who had only taken up the instrument six months earlier. Taking their name from a line in a William Blake poem, The Doors became the house band at the Whisky a Go Go club in West Hollywood and landed a recording contract with Elektra. Encouraged to express themselves by producer Paul A. Rothschild and engineer Bruce Botnick, they recorded their self-titled debut album in a week and reached No1 with their second single, `Light My Fire'.

The refusal to change the lyric `girl, we couldn't get much higher' for an appearance on The Ed Sullivan Show seemed to ignite Morrison's penchant for confrontation and he was charged with indecency and public obscenity after launching into a tirade against the New Haven police in December 1967. An increasing reliance on drink and drugs exacerbated tensions in the studio, too, with Rothschild rejecting `The Celebration of the Lizard' for the third album, Waiting for the Sun, after Strange Days and its spin-off singles had under-performed.

With Mickey Blythe and Kevin Krasny nimbly editing Paul Ferrara's concert footage (which was shot for yet another unrealised Doors project), DiCillo tells a compelling story, which he punctuates with performance footage of hits like `Hello, I Love You', `Touch Me', `LA Woman', `Love Her Madly' and `Riders on the Storm'. But, apart from allusions to Manzarek's familiarity with Bach, Krieger's love of flamenco and Densmore's jazz leanings, he skirts a discussion of the band's distinctive sound.

More frustratingly, he contents himself with rooting Morrison's increasingly unpredictability in the assassinations, alienations and demonstrations that shook 1960s America. Thus, there's no psychological insight into notorious incidents at the Singer Bowl in New York and the Dinner Key Auditorium in Miami, the latter of which resulted in the six-month prison sentence for exposing his genitals and simulating oral sex that was still hanging over Morrison when he died of a heart attack in a Paris bathtub on 3 July 1971 at the age of 27.

The commentary is occasionally florid and the chronology a touch circuitous. Moreover, some of the images used to define the decade are beyond clichéd. But DiCillo wisely eschews speculative and hindsight-strewn talking head contributions, while his enthusiasm for the band and fascination with Morrison should entertain aficionados and send the lapsed back to their record collection.