Gangster Nick Ferraro, who has been living in Naples since his deportation from the United States, is anxious to return to the States to put his lucrative enterprises in order. To accomplish this, he and his cohorts in the States and Mexico--Corle, Thompson and Martin Krafft--select an unwitting gambler named Dan Milner, whose weight and height match Ferraro's, to provide Ferraro with a new identity. Corle offers Dan $50,000 to go to Mexico for a year, without revealing who is paying him or why. Broke, Dan accepts the initial $20,000 payment and travels to Nogales, Mexico, to receive further instructions. While waiting for a plane to take him to his final destination, Dan meets Lenore Brent, a beautiful heiress and polished singer. To his surprise, he and Lenore board the same charter plane, which Dan finally learns is headed for Morro's Lodge in Baja California. At the remote, exclusive resort, owner José Morro questions Dan about his background, while guest Myron Winton, an investment banker, fills him in on some of the lodge's more mysterious guests, including Krafft, who is posing as a chess-playing writer. Dan then meets Hollywood actor Mark Cardigan, who is also an avid hunter. Dan soon becomes suspicious of Krafft and Thompson after he discovers they have bungalows next to his. Anxious to know what is going on, Dan confronts Krafft and the gun-wielding Thompson, who give him another $10,000 and assure him that he will find out more from a man who is en route to the lodge. The next day, after noticing Myron flirting with Jennie Stone, an unhappy newlywed, Dan deduces that Lenore is having an affair with Mark. Unknown to Dan, Lenore is actually Liz Brady, a former singer who is posing as an heiress in order to marry Mark, who is estranged from his wife Helen. After the soft-hearted Dan helps Jennie's husband Milton beat Myron at poker and thereby eliminate his debt to the banker, he asks Morro about the man he is to meet. Morro claims ignorance, then tries to discourage a drunk pilot, Bill Lusk, from landing at the resort, as a serious storm is approaching. Dan and Lenore watch Bill crash-land near the lodge, and in the moonlight, Dan impulsively kisses Lenore. The next day, Mark's personal manager, Gerald Hobson, arrives at the lodge with Helen, who has halted her divorce proceedings and wants to rejoin her husband. Mark rejects the idea, even though Gerald warns him that his publicized affair with Lenore could cost him his career. Dan then corners Bill and accuses him of faking his drunkenness. Bill confesses that he is an undercover Immigration Department agent and reveals that Dan has sold his identity to a notorious gangster, who has hired Krafft, an ex-Nazi plastic surgeon, to alter his face to resemble Dan's. Despite Bill's warnings, Dan refuses to cooperate with the agent, and later, while searching Morro's office, Bill is caught by Thompson and murdered. After Dan and Lenore come across Bill's body on the beach, Dan orders Lenore to leave the lodge out of concern for her safety. In his bungalow, Dan then is accosted by Thompson and two thugs and announces he is backing out of the deal. The thugs outdraw Dan, but Dan is able to alert Lenore to his predicament before he is forced into the boat that is to take him to Ferraro's yacht. Lenore entreats Mark to come to Dan's rescue, and Mark, anxious to prove he is a genuine hero, eagerly accepts the challenge. Dan, meanwhile, manages to escape from Thompson and swim to shore, but as soon as he tells Mark that the man on the boat is Ferraro, he sneaks back onto the yacht. Dan is soon being chased by the ship's crew and, despite shooting holes in the ship's steam pipes, is captured and brought to Ferraro. The gangster condemns Dan as a "welcher" and orders his men to beat him, then forces him to repair the steam pipes. Meanwhile, on the beach, Mark uses his hunting skills to pick off Thompson and his cohorts and leads the Mexican police and some volunteer fighters to Ferraro's yacht. Realizing that his scheme is doomed, Ferraro prepares to shoot Dan, but is stopped by the arrival of Mark and the police. While they and the ship's crew engage in a gunfight on the deck, Krafft suggests to Ferraro that he can inject Dan with some anesthesia, which will render him helpless and cause him to develop amnesia and die within a year. Desperate, Ferraro orders that Dan be injected, but Dan struggles and prevents the needle from pricking his skin. Ferraro and his men are finally routed, and later, while the Shakespeare-quoting Mark is hailed as a real hero by the press, Lenore, who has confessed her impersonation, gives up her gold-digging ways and pledges herself to Dan.