The Big Caper (1957)

A con man in debt and down on his luck comes up with what he thinks is the perfect caper--robbing a small-town bank that keeps a lot of money on hand because of the payroll of a nearby army base. He convinces a vicious crime boss to bankroll his scheme, but when he and his boss' girl move into the town to make preparations for the heist, he begins to have second thoughts about the whole operation.