Young newsboy Roger Mobley and an old man friend of his Don Beddoe find a briefcase in a vacant lot that was presumably thrown by bank robber Johnny Seven to avoid getting caught. Beddoe opens the briefcase in a filling station bathroom and says it's empty to the cops Robert Stevenson and reporter Richard Crane.
But Seven is coming back for his stolen loot and despite protestations to the contrary he's convinced Mobley or Beddoe or both of them have it. He's already risked time in the federal penitentiary for bank robbery so he wants his money.
The Boy Who Caught A Crook is a nice, but below average kid's film with a few too many holes in the story to be terribly convincing to anyone over 14. Wanda Hendrix turns in a nice performance as well as Mobley's widowed mother. In fact the whole cast is decent and sincere, but the film just doesn't rise above mediocrity.
And I guess the title itself gives it all away.