As he steps out of Los Angeles' Union Station, ex-convict Rocky Mulloy, fresh from serving five years of a life sentence for robbery and murder, is greeted by Lt. Gus Cobb, the detective responsible for his incarceration. With Gus is Delong, the decorated, disabled Marine who provided Rocky with the alibi that finally freed him. The cynical Gus invites Rocky and Delong for a drink, and at the bar, Delong explains that, because he shipped out the day after the holdup, he was unaware that Rocky, with whom he and some other Marines had been drinking the night before, was in trouble. Despite Delong's statements, Gus remains convinced that Rocky committed the robbery and informs him that he will be following Rocky until he leads him to the holdup money, which was never recovered. Once alone with Rocky, the alcoholic Delong admits that he concocted the alibi, hoping that the grateful ex-convict would share some of his loot with him. Rocky repeats that he did not commit the robbery, but knows who did and intends to find the money. Delong accompanies Rocky to a trailer park, where Nancy Morgan, the wife of his best friend Danny, who was also found guilty of the holdup and is still in prison, lives. Rocky and Delong rent a trailer near Nancy's, and she is thrilled to reunite with Rocky, with whom she was once romantically involved. That night, Rocky goes to see racketeer Louie Castro, who engineered the holdup, and accuses him of a frame-up. The gun-wielding Rocky demands that Castro pay him $50,000, the amount Castro had offered him to participate in the holdup, but Castro refuses. Instead, Castro gives Rocky $500 with which to place a bet on a fixed horserace running the next day. Later, at the trailer park, Rocky is shot at by an unseen assailant, and the still-enamored Nancy begs Rocky to drop the matter. Rocky dismisses Nancy's concerns and goes to see Arthur Fletcher, a witness who provided damning testimony during Rocky's trial. From Fletcher's wife Alice, Rocky learns that the now-dead Fletcher received $5,000 shortly after the trial and assumes that Castro bribed him. Following Castro's directions, Rocky then places his bet with a bookie named Harry and the longshot horse wins. Rocky's instant cash flow soon dries up when Gus reveals that the money is stolen. To prove his innocence, Rocky takes Gus to Harry's place, but the bookie operation has completely disappeared. In Rocky's presence, Gus telephones Castro and asks him if he has seen Rocky recently. When Castro claims that he has not, Gus, who has been following Rocky, knows that he is lying but is still reluctant to believe Rocky's story. Soon after, at the trailer park, Delong and his girl friend Darlene are mistaken for Rocky and Nancy by Castro's thugs and are shot in a hail of bullets. Darlene is killed instantly and the wounded Delong is rushed to the hospital. Gus brings Rocky and the shaken Nancy in for questioning with Castro, but cannot coerce them to admit anything. Later, an incensed Rocky finds Castro in his office and forces him at gunpoint to lie down on the desk. He then plays Russian roulette with Castro until he admits where his half of the loot is hidden. The terrorized Castro also reveals that Nancy has the other half, as Danny, unlike Rocky, agreed to participate in the holdup and committed the murder. After Rocky tricks Castro into calling his men to his office, he notifies the police. As the thugs and the police engage in a shoot-out, Rocky informs Gus where to find Castro's half of the money. At the trailer park, Rocky then confronts Nancy, who admits that she has the money but insists that she kept silent about it only because she was afraid of Castro. Nancy also confesses to shooting at Rocky to stop his snooping. Declaring that she has always loved him, Nancy begs Rocky to run away with her. Rocky agrees, but as soon as he leaves her trailer, he tells Gus about Nancy's deception and walks quietly away.
