The Manacled (1957)

The Manacled (1957) Sgt. Rockwell is an honest cop, but $50,000 is enough to tempt even someone like him. He's transporting a prisoner on a passenger train. The man is Stephen Fontaine, a thief with the silver tongue of a devil. As the sergeant leafs through a magazine about sports cars, Fontaine tells Rockwell that a pickpocket on the train has put an envelope in Rockwell's jacket pocket. Rockwell checks, and sure enough it's there. Inside the envelope is a key. Fontaine tells the sergeant what it opens, where to get in and what's inside. $50,000. All the sergeant has to do is let his prisoner escape.