Courtyard (1955)

A teenager escapes from a reformatory which is like a penitentiary. He is taken in by a nice itinerant musician, but there's a theft in the busker's landlady's house and the adolescent is immediately the ideal suspect, because he had been in the reformatory for pilfering. He investigates on his own and discovers that the culprit is the landlady's own nephew. His mother understands that her duty is to take her son back home.