Directed by Amy Berg. Cineworld, 6pm *****

Among the lesser achievements of this superbly gripping – and enraging – documentary from Amy Berg is its confirmation that celebrities really can make a difference. Having heard the story of three young men almost certainly falsely imprisoned for the murder of three Arkansan boys in 1993, such good eggs as Peter Jackson, Eddie Veder and Henry Rollins came together to campaign for their release. Berg lucidly explains how depressingly uninterested the authorities were in reopening a case they felt conveniently tidied away.

It seems depressingly unsurprising that one of the accused, Jessie Misskelley Jr, was mildly retarded, and was coaxed into his incriminating testimony by a canny, cynical prosecution. Certain wounds that formed part of the forensic evidence turned out to have been inflicted by animals after the event.

Berg has already shown her skill for documentary narrative in the brilliant Deliver us From Evil – a better study of clerical abuse than Mea Maxima Culpa – and the new film is every bit as well-structured as its predecessor. It also confirms that the greatest enemy of justice is very often not wickedness, but stubborn, lazy complacency. This is an important document and a faultlessly compelling thriller.