Gillies MacKinnon has often chosen to spotlight family relationships, particularly from the vantage point of a child. Lex, the teenager in Small Faces (1995), tried to negotiate his identity through the Glasgow badlands. Bea and Lucy, the young girls in Hideous Kinky (1998), played reluctant grown-ups travelling round Morocco on the whim of their mother during her naive searches for spiritual enlightenment.

His new film Pure, this time located in the streets of London, close to West Ham’s football stadium at Upton Park, is no exception. Ten-year-old Paul, the central character of the piece, takes responsibility for looking after his mum Mel, who is addicted to heroin, and his younger brother Lee, following the death of his father. Battling against her dealer Lenny, he unsuccessfully attempts to help her break the habit when her best friend dies of an overdose. Threatened with losing her children to her in-laws, Mel finally checks into a hostel to escape Lenny and clean up. Meanwhile Paul, approached by a detective inspector, manages to assist the police with Lenny’s arrest when he is caught using the local café as a supply route. By the film’s close, Mel manages to persuade the social services that she is a fit mother.

Molly Parker is as adaptable as ever, and as she proved in Wonderland (1999), she is entirely at home in a London milieu. She plays Mel with appropriate complexity: destructive and self-pitying, angry with a husband who has died, leaving her with bills to pay and two boys to look after, she has all the self-obsession of an addict for whom the next high is the most important and immediate consideration. She forgets Paul’s birthday, for instance, and does not refuse when he prepares her a fix. Clearly though, she loves the children deeply, and tries ultimately to be a better parent. The moments when her behaviour jars are the fault of the script rather than the actress: the fact that she give away her friend’s daughter on a bus seems odd and certainly reduces audience sympathy. A result of the drugs, perhaps?

And yet, despite the title, Pure really doesn’t feel like a drug movie. Addiction plays its part, but it could be alcohol or gambling as much as heroin. This is no Trainspotting or Naked, and unlike other films of this ilk, it does not espouse the gritty realism one might expect. With music by Nitin Sawhney and a colourful backdrop shot by director of photography John de Borman, it creates an unusual (and at times refreshing) sense of a specific location. But at the same time it feels very localised, occasionally too much so, never attempting to cast its net any wider to hint at a world beyond that of its characters, and fading a little too quickly from the viewer’s mind.