A police detective investigates a police suicide and goes after a crime syndicate that leads him to a series of murders.
Bertha Duncan (Jeanette Nolan) finds her husband Tom has killed himself and calls Mike Lagana (Alexander Scourby), who calls Vince Stone (Lee Marvin). Sergeant Dave Bannion (Glenn Ford) investigates, but Bertha does not tell him about the envelope Tom left. She says he had a pain.
Bannion has dinner with his wife Katie Bannion (Jocelyn Brando). At a bar he questions Lucy Chapman (Dorothy Green), who says Tom was getting divorced. She says he would not kill himself and that Bertha lied. Bannion goes back to Bertha, who says Lucy lied about the divorce.
Bannion learns that Lucy was murdered. Lt. Ted Wilks (Willis Bouchey) tells Bannion to stop bothering Bertha. Bannion questions the bar owner (Dan Seymour), who avoids answering. At home Bannion gets a threatening phone call and goes to the police-guarded mansion of Lagana. Bannion says that Lucy was tortured. He castigates Lagana and slugs his bouncer.
Lt. Wilks reprimands Bannion. At home Katie tells him not to compromise, and they kiss. When she starts the car, it explodes. Police Commissioner Higgins (Howard Wendell) tells Bannion it was probably revenge. Bannion suspects Lagana, and Higgins fires him.
Bannion is leaving his house and rejects help from detective Gus Burke (Robert Burton). Vince and Lagana call on Debby Marsh (Gloria Grahame). Lagana blames Larry Gordon (Adam Williams) for botching the murder of Lucy and for killing Katie.
Bannion questions a junkyard owner, but a woman says she took a message from Larry. Bannion asks his friend Al to call the bar at 9:30 and ask for Larry. Vince burns a woman, and Bannion accuses him of torturing Lucy. Debby offers Bannion a drink and follows him. They go to his hotel, drink, and talk before she leaves.
Vince twists Debby’s arm and throws coffee on her face. He calls Lagana, who wants Debby lost. She goes to Bannion with a bandaged face and says that Larry was there. Bannion gets her an unregistered room.
Bannion finds Larry and chokes him to get answers, taking his gun. Vince tells Lagana that Larry was killed. Lagana gets a call from Bertha, who says Bannion is there. Bannion accuses her of blackmailing Lagana and chokes her, but police arrive.
Bannion takes dinner to Debby and says he almost killed Bertha. Bannion goes to protect his daughter and finds that Al has veterans as bodyguards for her. Lt. Wilks and Burke show up too. Debby goes to Bertha and shoots her dead. Debby throws coffee in Vince’s face, and he shoots her. Bannion comes in, and Debby says she killed Bertha. Bannion fights and captures Vince. Lt. Wilks and Burke come in and take Vince. Bannion tells Debby about Katie, and Debby dies.
Lagana and Higgins are indicted, and Bannion goes back to working for the police.
This classic film noir reflects the increased awareness of the problem of organized crime in cities after the Kefauver hearings.