Billy Dannreuther is a formerly-wealthy American who has fallen on hard times. He is reluctantly working with four crooks: Peterson, Julius O'Hara, Major Jack Ross and Ravello, who are trying to acquire uranium-rich land in British East Africa. Billy suspects that Major Ross murdered a British Colonial officer who threatened to expose their plan. While waiting in Italy for passage to Africa, Billy and his wife Maria meet a British couple, Harry and Gwendolen Chelm, who plan to travel on the same ship. Harry seems a very proper and traditional Englishman, while Gwendolen is flighty and a compulsive fantasist. Billy and Gwendolen have an affair, while Maria flirts with Harry. Peterson becomes suspicious that the Chelms may be attempting to acquire the uranium themselves. Though this is untrue, it seems confirmed by Gwendolen, who lies about her husband and exaggerates his importance. File:Beat the Devil (1953).webm Sea-sick Harry and Gwendolen on board Billy and Peterson decide to take a plane instead, but their car runs over a cliff when they are pushing it after a breakdown and the pair are wrongly reported to have been killed. In order to replace Peterson's lost capital, Ravello approaches Harry Chelm and explains their scheme. Just then, to everyone's surprise, Billy and Peterson return to the hotel unharmed, just as the purser announces that the ship is at last ready to sail. On board, Harry reveals that he knows about Peterson's scheme and intends to inform the authorities. Peterson orders Major Ross to kill Harry, but Billy thwarts the murder attempt. Disbelieving Harry's outraged accusations, however, the ship's drunken captain has Harry locked in the brig. The ship's engine malfunctions and the passengers are told to escape by lifeboat. When Billy goes to rescue Harry, he finds that he has freed himself and left the ship, intending to swim ashore. Having abandoned ship, the passengers land on an African beach, where they are arrested by Arab soldiers. They are interrogated by Ahmed, an Arab official who suspects that they may be spies or revolutionaries. Billy creates a distraction by fleeing the room, and befriends Ahmed when he is recaptured by talking to him about Rita Hayworth, whom he pretends to have known. Billy then persuades him to send the party back to Italy by sailing boat. After the party land, they are questioned by a Scotland Yard detective, who is investigating the murder of the Colonial officer. Just as he seems taken in by Peterson's smooth talk, Gwendolen reveals Peterson's scheme, his involvement in the murder and his attempt to kill Harry. The detective promptly arrests Peterson, O'Hara, Ross, and Ravello. As the four crooks are led away in handcuffs, Gwendolen receives a telegram from British East Africa saying that Harry has acquired the land where Peterson and the others were aiming to enrich themselves; he is now extremely wealthy and willing to forgive Gwendolen. Billy laughs happily, saying "This is the end, the end!"