At the end of World War I, a division of the French Foreign Legion led by Major Foster (Gene Hackman) has been ordered to protect an archaeological expedition led by Marneau (Max Von Sydow). The last expedition was destroyed along with its legionnaire guards but Foster must follow orders, despite his opposition to what he believes is "grave-robbing".

The excavation incites the wrath of EI Krim (Ian Holm), a powerful Arab leader who uses it to arouse religious fanaticism amongst his tribes and lead an attack on the foreigners.