The passengers of a steamer are in port in Italy en route to British East Africa. Billy and Maria Dannreuther (Humphrey Bogart and Gina Lollobrigida) once owned a fine home in the area, but now in reduced circumstances. So it’s no wonder Dannreuther is banking on a tip that would make him wealthy. He plans to head for Kenya to purchase land purported to be rich with uranium ore. Paying heed to the rumor are an odd array of swindlers: an Englishman named Peterson (Robert Morley) and his shady associates O'Hara (Peter Lorre), Ross and Ravello. While her husband is occupied, Maria finds herself intrigued by handsome Harry Chelm (Edward Underdown), an upper crust Briton who is also Africa-bound. He is traveling with his wife, Gwendolen (Jennifer Jones). She is essentially neglected, left to reading or entertaining herself. Are the Chelms also in pursuit of the uranium? Once aboard ship, all these passengers’ machinations make their lives more and more entangled. Their individual greed becomes more apparent as they reach their destination.