Junkhearts

British film-makers tend towards bipolarity. Where French cinema is broadly speaking about the middle classes, we tend to get films about one thing or the other. The national fixation with the past supplies stories about how the nabobs of yore lived (and, as importantly, dressed). But from Ken Loach onwards, British directors of another cadre have always had a real feel for the street, for that tranche of society which bumps along with nothing, where substance abuse is the rule rather than the exception. Such a film, more or less, is Junkhearts.

Tinge Krishnan’s big-screen debut as a director offers a nightmare vision of survival on the pavement, where the homeless and the addicted live by their own rules without, it would appear, any support from society. This is Broken Britain, as it's currently called, in action. Eddie Marsan plays Frank, a former soldier who once served in Northern Ireland, now living alone in a council high-rise. The burst capillaries spreading across his cheeks speak of long dedication to the bottle. The booze is only half successful at keeping demons at bay: post-traumatic stress disorder brings alive brutal memories, hallucinations so real they seem to invade the room, in one of which he accidentally killed an innocent woman.

Simon Frank’s script bypasses plausibility as it beats a path towards a redemptive finale

In one of Frank's more lucid interludes he takes pity on a young homeless woman called Lynette (Candese Reid). They strike up a terse kind of rapport and he is soon offering her shelter, feeding her, teaching her self-defence and trying (though failing) to get her into some kind of training. It’s apparent that Lynette fills a gaping void left by the loss of contact with a daughter. She equally has found a father figure. The modest optimism created by this oddball liaison can’t last of course. Lynette duly introduces her boyfriend Danny (Tom Sturridge), a saturnine figure from Belfast whose accent stirs up all too vivid memories for Frank. Frank’s good nature is preyed upon, he is stuck back on the bottle like a baby on a teat and even a brief sexual liaison brings no comfort. As his judgment blurs and his defences are lowered, the flat becomes party central, then a safehouse for drug dealing and finally a crack den.

If this were all the film had to offer it would be a successful portrait of a decent man’s failure to escape the clutches of alcoholism. But early on we are introduced to an apparently well-to-do woman called Christine (Romola Garai, pictured right). It emerges in fleeting glimpses that she is a single mother whose swanky media job cannot support both a nanny and weekends of high heels and hedonism. It looks as if Christine is there as one half of a two-stranded narrative: that life deals out its troubles democratically. But Garai soon drops out of the film and only returns for a conclusion which feels too pat.

Simon Frank’s script, while steady and certain in depicting the trauma of addiction, bypasses plausibility as it beats a path towards a redemptive finale. Krishnan’s cast is impressive but the reason, ultimately, to see Junkhearts is Marsan. He’s always a watchable actor but, without resorting to theatrics, here he gouges a performance out of himself that tells an awful truth.

• Junkhearts is on UK release from Friday

Watch the trailer to Junkhearts