Adapted from the novel by W. R. Burnett, a clerk is mistaken for an escaped murderer, who uses his likeness to escape the police.
After eight years of never being late, Arthur Ferguson Jones (Edward G. Robinson) oversleeps. Miss Clark (Jean Arthur) comes in late and is fired. "Killer" Mannion escaped from prison and looks just like Jones. Mr. Hoyt (Donald Meek) calls the police to get Mannion, and they arrest Jones. He says he is not Mannion, and they question Miss Clark. The boss J. G. Carpenter (Paul Harvey) does not know Jones; but Slugs Martin (Edward Brophy) identifies Jones as Mannion. The police learn that Mannion just robbed a bank, and Seaver (Etienne Girardot) identifies Jones. Fingerprints don't match, and Jones is released. Slugs asks for protection. The district attorney (Arthur Byron) gives Jones a letter that he is not Mannion so he won't be arrested.
J. G. apologizes to Jones, and reporter Healey (Wallace Ford) asks Jones to write stories for the paper. They smoke cigars and drink. Jones, drunk, kisses Miss Clark, gets her rehired, and takes the afternoon off. Jones finds Mannion (Edward G. Robinson) in his apartment. Mannion asks for the letter in order to use it at night. Mannion tells Jones not to talk or else he'll be killed. Mannion goes out and comes back in the morning. The paper says he killed two guards and has an article by Jones on Mannion. Jones goes to work and tries to reach Healey about an article saying Mannion has false courage. Miss Clark tells Jones she got him $250 a week from Healey. Jones won't let Miss Clark come in. Mannion complains about the article and dictates one to Jones. The FBI reads the article and suspects Jones. The district attorney orders Jones arrested so that police can shoot Mannion. Miss Clark goes to Jones' apartment to give him his check. Mannion lets her in and kisses her. Miss Clark tries to call the police but is stopped. The district attorney and mayor tell Jones he is being put in prison.
Jones goes to get his things with detectives Boyle (Arthur Hohl) and Howe (James Donlan). Jones finds Mannion asleep, takes his gun, and hands it to him. Mannion leaves with a suitcase and calls his men to get Jones. Mannion plans to get Slugs in prison, where the warden (J. Farrell MacDonald) wonders if Jones is Mannion. Mannion kills Slugs and goes with Seaver in the police car. Mannion has Jones tied up but lets him go to take his money to the bank for his mother to get him killed. Police prepare at the bank. Jones forgot the money, goes back, and is mistaken for Mannion by his men. Jones as Mannion tells them to plug Jones, and they shoot Mannion. Jones as Mannion picks up a machine gun and orders them into a room. He finds Clark and Seaver and then faints. Jones gets the $25,000 reward and goes to Shanghai with Miss Clark.
This gangster comedy plays upon the contrast between the shy clerk and the aggressive murderer amid the hysteria of news reports and police efforts to catch him.