P.C. Wren’s 1924 novel. French troops in the Sahara arrive at a fort mysteriously occupied only by dead men. Flashback to England, where orphaned brothers Michael, Digby and John Geste are raised by their aunt, Lady Brandon. When Lady Brandon's heirloom, the Blue Water sapphire, vanishes, Michael nobly takes the blame and runs away to join the Foreign Legion. Digby and John follow. Amidst dramatic events and years wandering the North African desert, two of the brothers die. The third returns to England, and the theft of the Blue Water is finally solved. The preposterous but lively plot is rendered in a surprisingly sophisticated style, though marred by the seemingly-reflexive anti-semitism that was common among English writers pre-WW2.