A down-on-his-luck ex-GI finds himself framed for an armored car robbery. When he's finally released for lack of evidence--after having been beaten up and tortured by the police--he sets out to discover who set him up, and why. The trail leads him into Mexico and a web of hired killers and corrupt cops.

After being dumped by his fiancée, hard-drinking and depressed Mark Cormack (John Payne) loses his job in the Los Angeles district attorney's office and serves as bouncer in a Las Vegas casino. A wheelchair-using stranger Barzland (Francis L. Sullivan) hires him to locate a ruby that disappeared in a Caribbean plane crash. He lures Cormack into doing the job by telling him it may be in the possession of the very woman who jilted him. The ex-detective flies to remote island Santo Rosario to find the stone and investigate the mystery. When he finds his old flame he finds that her husband is in prison. Cormack, again falling for Janet, is convinced into helping him break out of jail. But Janet has other plans.