A 1966 American adventure film based on the 1924 novel by P.C. Wren, filmed by Universal Pictures in Technicolor and Techniscope near Yuma, Arizona, directed by Douglas Heyes. Two brothers, Beau and John Geste, join the French Foreign Legion, where they fall under the rule of tyrannical Sergeant Markoff, aware of a dark family secret concerning a fabulous jewel one of them carries. As tensions rise, Arabs attack the fort, and rivalries must be thrown aside in a desperate battle for life.