When a 10-year-old commits a horrendous crime, whose fault is it? "Boy A" addresses the question but offers no easy answer in this painful portrayal of the repercussions of a childhood gone terribly awry.

Irish director John Crowley ("Intermission") keeps the story elegantly simple, drawing minimal strokes to maximum effect — the boy's home life, for example, is told in brief compositions: a father who spends entire afternoons in front of the TV, an ashtray and a bottle of whiskey at his side, a mother with cancer who's too absorbed in her symptoms to pay any attention to her son. The boy (Alfie Owen) is bullied at school and ignored by his teachers, and when he fails to show up for classes, no one takes any notice. The only person who befriends him is Philip (Taylor Doherty), a boy just as lonely, but bolder and sneakier, with a cruel streak that he makes no attempt to hide.

Fourteen years later, the boy has a new name: Jack Burridge (Andrew Garfield) — just out of a special prison for delinquents and gingerly trying to make a new start in a new city, Manchester. Terry (Peter Mullan), the social worker who has looked after him all these years, gives Jack a celebratory gift of a pair of sneakers inscribed with the word "escape" — a little joke that makes them both chuckle. Jack was lucky: He has grown into a lanky and handsome youth with a charming, disarming naivete that Terry obviously treasures. Philip didn't have a second chance, having died in prison seven years earlier (whether by suicide or the result of a lynching is never made clear).