Lt. Leonard Diamond (Cornel Wilde) is on a crusade to bring down the powerful crime czar Mr. Brown (Richard Conte), and he has used public funds in his quest, which has brought him under the scrutiny of Captain Peterson (Robert Middleton). On top of that Diamond tries to woo Susan Lowell (Jean Wallace), the girlfriend of Brown, who is under constant surveillance by Mingo (Earl Holliman) and Fante (Lee Van Cleef), some of Brown’s goons. In the meantime, archrival Joe McClure (Brian Donlevy) wants to take over the crime business, but meets some double-crossers in Mingo and Fante who remain loyal. Mr. Brown has no such honor and will sacrifice anyone to save himself.