Vela, the cynical captain of a dilapidated sailing ship, offers passage out of Germany to fugitives. His crew members are also not trustworthy. Cheyne, a young American doctor visiting the ship, is forced to join a 3-month voyage to Brazil when Vela sets sail unexpectedly. In the middle of the ocean, Cheyne saves the lone survivor of a plane crash, the beautiful American heiress Ethel Marley; he and the ship's cook keep her hidden from the captain and crew. However, a violent incident leads to mutiny and murder, putting the two Americans in grave danger, leading to a suspenseful and dramatic climax.