Although he's been demoted for political reasons, public outcry forces the mayor to take more aggressive action against sleazy gang boss Sam Belmonte, and Fitzpatrick is promoted to police chief.

His younger brother, Police Detective Ed Fitzpatrick, allows himself to be seduced by a languorously sexy Belmonte gang moll, Daisy, and needs money to continue the relationship.

Frustrated when his principled brother will not promote him, he betrays Jim's trust by conspiring with Belmonte's henchmen in a truck hijacking that results in the deaths of a child and another police officer.

After the guests flee, a huge gun battle erupts between the police and gangsters; everyone dies, including Daisy, hit by a stray bullet.

[1] The Beast of the City originated in consultations between MGM head of production Louis B. Mayer and President Herbert Hoover, who was concerned that the public needed to have greater respect for police officers and other law-enforcement officials.