Frank Warren is a treasury agent assigned to put an end to the activities of a powerful mob crime boss. Frank works undercover, posing as a criminal to seek information, but is frustrated when all he finds are terrified witnesses and corrupt police officers.
Poker Player (uncredited)
A shell-shocked young GI mistakenly believes he is dying, and a young artist takes it upon herself to prove to him that he's not.
Dealer
When an employee at an illegal gambling den dies suspiciously, her sister, Nancy, looks into the situation and falls for Johnny O'Clock, a suave partner in the underground casino. Selfish and non-committal by nature, Johnny slowly begins to return Nancy's affection and decides to run away with her, but conflict within his business threatens their plans. As Johnny tries to distance himself from the casino, his shady past comes back to haunt him.
Man (Uncredited)
A daily news editor recalls a married detective and the deadly woman behind his downfall.
Policeman (Uncredited)
After a rare gem is stolen from an exhibition at a posh hotel, Inspector Farraday decides to recruit former thief Boston Blackie to find the stone. Along with his assistant, "The Runt", Blackie focuses his investigation on the hotel manager, George Daley, and his sister, Eileen. Through disguises and ruses, Blackie and the Runt try to trick their way to discovering the thieves.
