The disappearance of a fabulous sapphire dubbed the Blue Water sends the British Geste brothers -- "Beau" (Gary Cooper), John (Ray Milland) and Digby (Robert Preston) -- off to join the French Foreign Legion, leaving England in disgrace. Assigned to a North African command, the siblings find themselves in more danger from their unhinged, sadistic sergeant (Brian Donlevy) than from marauding Arab rebels. Based on P.C. Wren's epic adventure novel.