In a dark Washington, DC apartment, two men beat up another man and leave him for dead.  A short time later, police captain Finlay, who has been called to the murder scene, questions Miss Lewis, the woman who discovered the body.  Miss Lewis tells Finlay that, earlier in the evening, she and the victim, Joseph Samuels, were drinking in a bar with a trio of recently discharged soldiers, one of whom Samuels then invited to his apartment.

After Miss Lewis states that she left Samuels alone with the soldier, returning only after Samuels failed to answer his phone, army sergeant Montgomery appears at the door, looking for Corporal Arthur "Mitch" Mitchell.  Montgomery claims that he and another friend, Floyd Bowers, were with Mitch in Samuels' apartment, but that Mitch left abruptly, promising to return soon.  As he has found the Corporal's wallet in the apartment, Finlay determines to locate Mitch and brings in his best friend, Sergeant Felix Keeley, for questioning.  While maintaining his friend's innocence, Keeley tells Finlay that Mitch, a painter, is suffering from post-war depression and is estranged from his wife Mary.  Finlay then re-questions Montgomery, a former policeman, who describes Samuels as a draft-dodging "Jewboy."  Montgomery repeats that, after following Mitch to Samuels' apartment, he and Bowers left shortly after Mitch.

Concerned for Mitch, Keeley sends all of the servicemen in their hotel to search for him.  With his friends's help, the corporal manages to elude some M.P's, and flees to a movie theater with Keeley.  Mitch then tells Keeley his version of that night's events: After Samuels takes Mitch to his apartment, Montgomery bursts in with Floyd and picks a fight with Samuels.  Suddenly ill, Mitch leaves Samuels' and meets a sympathetic taxi dancer named Ginny Tremaine, who invites him to wait for her at her place.  There Mitch runs into an odd man, who claims at first to be Ginny's husband, then insists he is not.  Unnerved by the man, Mitch leaves and staggers back to the hotel.

Back in the theater, Keeley informs Mitch that Mary is in town, anxious to see him, then hears that Floyd has been found hiding out in Maryland.  Before the police can question Floyd, Montgomery appears at his door, demanding that they "get their story straight." A nervous Floyd agrees to corroborate Montgomery's story to the police and promises not to speak to anyone about the incident.  When Keeley and another soldier, Bill Williams, come knocking, Montgomery hides and eavesdrops as Floyd reveals that he called his friend Leroy, who was in the bar briefly with Mitch and Samuels.  After Keeley and Bill leave, an enraged Montgomery beats and strangles Floyd, leaving him for dead.

Later, Finlay questions Keeley about Floyd's murder and learns about Ginny.  Keeley then meets with Mary and directs her to the movie theater where Mitch is still hiding.  After reuniting with her confused husband, Mary offers to question the taxi dancer on his behalf and goes with Finlay to Ginny's apartment.  Neither Ginny nor the strange man, however, can provide a convincing alibi for Mitch.  Frustrated, Finlay re-interrogates Montgomery, who unwittingly exposes himself as the killer when he displays his hatred of Jews and thereby supplies a motive for the crime.  Delivering a passionate speech on the evils of anti-Semitism, Finlay then convinces a frightened Leroy, who has been found by Keeley, to participate in a plot to trap Montgomery.

In a men's room, Leroy tells Montgomery that he has just spoken with Floyd and that Floyd is demanding blackmail money from him.  After Leroy gives him an address for Floyd, which lists the correct building but the wrong apartment number, Montgomery sneaks into Floyd's apartment.  There he is startled to run into Finlay, who calmly points out that the only way that Montgomery could have known which apartment belonged to Floyd was if he had been there earlier.  In a panic, Montgomery runs out of the building, but is shot dead in the street by Finlay.