The Interrupters (12A)
dir: Steve James

If some cinemas have about them the air of the car-boot sale, that may be because the superhero genre is cleaning out its cupboards before the return next summer of Batman and Spider-Man. Following The Green Hornet, Green Lantern and Thor, who could blame Super Gran if she's waiting for a Hollywood suit to call?

A new documentary about real-life superheroism makes its fictional practitioners look pretty puny. The Interrupters profiles CeaseFire, a Chicago organisation that intervenes directly in confrontations in an effort to stem the city's death toll from gang violence. Sometimes the work takes the form of mediation or mentoring; just as often it is about wading into a fight or a flare-up and preventing the damage from becoming irrevocable. The violence interrupters, as this hands-on chapter of CeaseFire is known, don't wear capes or Lycra - but you wouldn't begrudge them if they did.

CeaseFire is comprised largely of former gangsters and gang lords, some scarred, others missing a digit or two, all of them giving off a vibe of fortified humility. As the organisation's director, Tio Hardiman, points out, the sort of people who trade gunfire in front of the school gates areunlikely to take kindly to just anyone suggesting they kiss and make up. Coming from street-corner legends such as Cobe Williams (12 years inside for drug trafficking and attemp­ted murder) and Eddie Bocanegra (14 years for murder), the invitation to lay down arms has a little more weight.

Cobe is a large man possessed of a lullaby voice; he is equally calm and compassionate whether trying to dissuade a volatile addict called Flamo (how's that for a name straight out of a Marvel comic?) from seeking revenge on a snitch or accompanying a young ex-con, L'il Mikey, on a peacemaking mission to the barbershop that he held up two years earlier. Meanwhile, Eddie includes among his weekly activities an art class at an elementary school. His pupils need only the slightest prompting to spill their hearts. Even with all he has seen and done, Eddie is taken aback when one fragile girl breaks down while talking about the shootings that make her young life a misery.

For most viewers, The Interrupters will be defined by the charismatic Ameena Matthews, daughter of the imprisoned gang leader Jeff Fort. We first meet her as she defuses a roadside ruckus that begins with one boy having his teeth knocked out, before escalating rapidly. Ameena identifies one volatile element, removes him from the scene for a chinwag and then simply takes him for a drive. Soon they are laughing with his pals on the stoop. The trick, she says, is to find the soft spot in a person: "Not weak. Soft."

The beauty of Ameena's efforts, and much of what CeaseFire does, is that they delve far beyond the symptoms. While Chicago's politicians debate bringing in the National Guard to tackle gun crime, Ameena is taking one 18-year-old hothead, Caprysha, for her first manicure - a moving event that ends with Caprysha gazing in disbelief at the pistachio-green nails on her baseball-mitt hands. It restores a tiny shard of the self-esteem that her absentee parents have done their best to demolish.

The Interrupters was inspired by a New York Times Magazine article by Alex Kotlowitz, and shot by a skeleton crew that included Kotlowitz as interviewer and Steve James manning the camera. As one of the three directors of Hoop Dreams, the 1994 documentary about high-school basketball prodigies, James is no stranger to shooting in fraught situations, or organising a multilayered narrative.

But the new picture is the more diffuse and less thorough piece. There are too many missing testimonies (it would have been instructive to hear from the police, say, or the gang members who are being interrupted) and dangling questions. The matter of those CeaseFire workers who haven't fully turned over a new leaf is raised briefly, while we meet one unlucky interrupter whose intervention was not met with fist bumps. Both these areas get such short shrift that it's tempting to wonder if a uniformly good press was the price of CeaseFire's full participation.

“The Interrupters" is released on 12 August