Brothers Beau, John and Digby Geste join the Foreign Legion, where they fall under the rule of tyrannical Sergeant Markoff. Beau and John are assigned to Fort Zinderneuf, where Markoff tries to break their spirit, 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.

Ann-Margret
as Flavia Geste

Marty Feldman
as Dagobert 'Digby' Geste

Michael York
as Beau Geste

Peter Ustinov
as Sergeant Markov

James Earl Jones
as Sheikh

Trevor Howard
as Sir Hector

Henry Gibson
as General Pecheur

Terry-Thomas
as Governor

Roy Kinnear
as Boldini

Spike Milligan
as Crumble