The opening scene of Boy A is a study in how to speak volumes with only a few words, a few props and a ton of body language. It literally sets the scene for the whole of the next two hours. Two hours of cinematographic magic, perfect storytelling and sublime acting that make you want to grab the people who refuse to fund British cinema by the throat and shake them, shouting "SEE? This is how it could be. We could have so many more like this!"

A middle-aged man sits opposite a younger man, perhaps in his early twenties. The younger has been tasked with deciding on a new name. Speaking volumes. He must be Boy A, he must need protection and a new identity, he must have moved away, the older guy must be his mentor. After some uncertainty, Boy A decides his name will be Jack. He faces an even more uncertain future and, as yet, we know nothing about his past. About what has brought him to be sitting at this table. John Crowley, in only his second feature film, tantalisingly reveals those details - both future and past - in one of the most distinctive and powerful films I've seen this year.

Terry (Peter Mullan), the older man, is indeed Jack's caseworker. His forte is helping traumatised young men overcome their pasts and build new lives. He travels with Jack (Andrew Garfield) to Manchester, and helps him settle into a sparse bedroom rented by a friendly but preoccupied woman, and, having warned him that his new identity is now the "real" person and his previous life must never be mentioned, leaves him to fend for himself.

Jack is a shy and awkward young man who was a shy and bullied schoolboy, with an alcoholic father and a cancer-ridden ineffectual mother. Beautifully hinted at with just a few short images, Jack's back story is built up in a series of claustrophobic flashbacks that tell as much about his mental state through camera work as they do through narrative. His bullies are dealt with by another young boy with whom Jack (then known by his real name Eric) develops a strong bond which is the source of his undoing. Because the other boy is an angry and damaged soul who eventually kills a young girl in Jack's presence, although we're never entirely sure whether Jack took any active part in the murder.

He paid for it though - serving a prison sentence before being taken under Terry's wing.

Back in the present Jack takes a job as a delivery driver and, slowly at first but with increasing confidence that is beautifully realised by Andrew Garfield, he begins to build relationships and friendships with his coworkers. One in particular, Michelle (Katie Lyons), an attractive young woman who works in the office, takes a shine to him. Inexperienced with women, Jack takes his time to respond to her advances but eventually he gets the idea and the two start seeing each other. Innocent and tentative at first, they soon develop deep feelings for each other and spend more frequent nights together.

Terry is extremely gratified by Jack's progress, lauding him as his "most successful project" and his pride is inflated even further when Jack pulls off a rescue of a young girl from a car crash.

But Terry's son who has moved back to be with his father after years of living with his estranged mother, is jealous of the attention and love Jack is receiving from Terry, and takes his revenge by revealing Jack's past to Michelle, his bosses and co-workers, and the press. Jack, isolated and hounded once more, escapes from his bedroom and heads for Blackpool where he and Michelle had spent some of their happiest times. Standing on the end of the pier gazing into the dark waters, he calls Terry and his workmate Chris to say goodbye.

The flashback device can sometimes be clumsy and invasive, but in Boy A it draws the viewer into a compelling narrative that gradually reveals not only Jack's past but his motivations and his challenges. Can a man ever leave his past behind and reinvent himself? That is the question at the core of the film, but unlike other similar tales, Boy A never takes the easy option. On one level Jack find happiness, but his increasing comfort with his new life is matched by increasing unease that he is living a lie, and hiding his dark truth from his friends and, especially, from the one he loves. Movingly, he tells Michelle "I never thought I would speak those words to a girl, or have them spoken to me," and the fact that he can never reveal the truth about himself begins to tear him apart, at least until the decision is taken out of his hands.

With a masterful script by Mark O'Rowe from the novel by Jonathan Trigell, perfect direction from John Crowley and near-perfect performances from everyone concerned (especially Katie Lyons from Green Wing in her first feature) Boy A deserved a much higher-profile slot. If you missed it and you have another chance to see it - take it!