Young petty crook Jackie Knowles (Richard Attenborough) is arrested for his role as getaway driver in a botched robbery. As Knowles is already on probation for an earlier crime, he is sentenced to three years in Borstal. Jackie intends to keep his head down and serve his time but soon falls in with a crowd that plan to escape. Scheming Alfie Rawlins (Dirk Bogarde) see's Jackie's innocent charm as integral to their escape plans and persuades him to join the gang. Jackie's anxiety is heightened by rumours of a romance between his girlfriend Kitty (Barbara Murray) and former Borstal boy Bill Foster (Jimmy Hanley). During the escape Jackie coshes a Borstal guard, and after they are all quickly recaptured, he learns the stricken officer is undergoing a life-saving operation that may lead to a murder charge if unsuccessful. It's left to Kitty and the Borstal's progressive governor (Jack Warner) to try and help Jackie serve his time, rehabilitate and not reoffend.