Shortly before Christmas in New York City, one-armed insurance investigator Jack Williams (Robert Swanger) is looking at a college yearbook photo of John Hansen when someone slips into his apartment and shoots him to death.

Hot-headed private investigator Mike Hammer (Biff Elliot), Jack's war buddy, vows to avenge his friend's death despite a warning from Pat Chambers (Preston Foster), captain of the homicide squad, to let the police handle the case.

Mike goes to see Jack's fiancée, Myrna Devlin, a torch singer and reformed drug addict, but she is too distraught to talk with him.

Because Pat has given him a guest list from Jack's recent party, Mike surmises that the police captain is using him to draw out the killer.

Mike begins his investigation, first visiting wealthy fight promoter and art collector George Kalecki (Alan Reed) in upstate New York.

Kalecki introduces his live-in friend, John Hansen, as college student Hal Kines (Bob Cunningham), and claims they were home together after the party.

Mike next visits alluring psychoanalyst and author Charlotte Manning (Peggie Castle), who was treating both Jack and Myrna.

Later at his office, ex-boxer Killer Thompson reveals to Mike and Velda (Margaret Sheridan) that Kalecki, his former manager, runs a numbers racket.

Mike slips into Jack's apartment through a window to avoid the policeman on guard, and finds a note from Pat, who anticipated his arrival.

Mike locates Eileen's father, veterinarian R.H. Vickers, who reveals that he had asked Jack to help his daughter after she ran away from college with John Hansen.

As before, Mike confides in Charlotte, with whom he has fallen in love, and tells her he believes that Kines worked the college campuses to recruit new thieves for Kalecki.

When Myrna is found dead in the street from a hit and run accident, the medical examiner finds the needle mark on her arm, prompting Pat to assume that she had returned to drug use.

The actresses were all bosomy stereotypes, including Peggie Castle, Margaret Sheridan, Frances Osborne, Mary Anderson and those riotous twin sisters Tani and Dran Seitz.