Brit Paul Bonnard (Rossano Brazzi) enlists gruff American Joe January (John Wayne) to help him find a hidden treasure that is worth a fortune. Before long, they are joined by prostitute Dita (Sophia Loren), who is moved by Bonnard's earnestness, and the three embark on a journey through the wild in hopes of finding an ancient lost city. They finally stumble upon the riches, but, after Bonnard feuds with Dita, he angrily takes the jewels and supplies, and leaves his partners to die in the desert.