Cody Jarrett (James Cagney) is the sadistic leader of a ruthless gang of thieves. Afflicted by terrible headaches and fiercely devoted to his 'Ma,' Cody (James Cagney) is a volatile, violent, and eccentric leader. Cody's (James Cagney) top henchman wants to lead the gang and attempts to have an 'accident' happen to Cody (James Cagney), while he is running the gang from in jail. But Cody (James Cagney) is saved by an undercover cop, who thereby befriends him and infiltrates the gang. Finally, the stage is set for Cody's (James Cagney) ultimate betrayal and downfall, during a big heist at a chemical plant.