A gang, led by a man who loves his mother more than his wife, is infiltrated by an undercover cop in prison and also has internal conflicts.
Cody Jarrett (James Cagney) and his gang rob a train and kill four men. Cody tells his wife Verna Jarrett (Virginia Mayo) to help Ma Jarrett (Margaret Wycherly). Cody does not trust Big Ed (Steve Cochran). Cody suffers a terrible headache, and Ma comforts him. Cody packs money they stole.
Police find a man dead from burns and learn of Jarrett's gang. Police follow Ma in three cars. She warns Cody, who wounds the cop Philip Evans (John Archer) as they leave. Police chase his car. Cody goes into a drive-in movie and tells Ma and Verna he is turning himself in for an Illinois rap.
Ma and Verna tell Evans that Cody is in Illinois. Evans assigns Hank Fallon (Edmond O'Brien) to go undercover as Cody's cellmate and transfers those who know him. Cody is sentenced to one year, and Fallon is sentenced as Vic Pardo. In prison Pardo sees Bo Creel, who may identify him, and so he gets into a fight and is put in solitary.
Ma tells the gang that Cody gets his full share of the robbery. Verna wants Ed to get rid of Cody. Ed's friend Roy Parker (Paul Guilfoyle) tries to kill Cody, but Pardo saves his life. Ma visits Cody and says that Verna ran off with Big Ed. She says she will kill Ed. Cody threatens Parker and gets a headache, but Pardo helps him.
Pardo offers to help Cody escape. Pardo tells his visiting "wife" to get a car for them. At a meal Cody learns that his ma is dead, and he fights the guards. A doctor commits Cody as homicidal, but Reader (G. Pat Collins) brings him a gun. Cody gets Pardo and Parker to go with him in a car with the doctor.
Evans learns that Cody escaped. Cody shoots Parker. Verna watches Big Ed put a bell on the door. She wants to leave, but Big Ed threatens to tell Cody that she killed Ma. At night Verna sneaks out to the garage, where Cody grabs her. She helps Cody sneak in, and he kills Big Ed.
Cody and his gang plan a robbery. Pardo asks about the trader. Daniel Winston (Fred Clark) tells Cody about a chemical plant. Pardo learns that Winston is the trader. Cody's men stop Pardo from leaving, and Pardo says he wants to see his wife. He fixes the radio and puts a device in the truck.
In a gas station washroom Pardo writes a message. Bo Creel drives the truck as Cody and his men hide inside. Evans gets cars to detect the signal. The truck goes in the plant, and the gang robs the office. Bo Creel tells Cody that Pardo is a cop. Pardo holds a rifle on them but is struck down. Evans tells Cody to surrender. Cody shoots, and the police use tear gas. Fallon (Pardo) comes out to Evans and tells him where to arrest Winston. Cody climbs to the top during the shoot-out. Reader surrenders, but Cody kills him. Fallon wounds Cody, who starts a fire and tells Ma he is on top of the world. Then the fire causes a big explosion of chemicals.
This crime drama reflects how more advanced police methods
are being used to catch a gang more typical of the 1930s. The
gang leader is portrayed not only as a sociopath but also as a