Foreign Legion Major Foster (Hackman), an American haunted by his memories of the recently-ended Great War, is assigned to protect a group of archaeologists at their dig. Foster's unit includes the charming, thieving rascal Marco (Hill), who joined the Legion only to avoid prison. After long stretches portraying the boredom and hardship of day-to-day life in the Legion, Foster's command occupies a small village where the archaeologists believe they've found a burial site sacred to the Arabs. An Arab leader (Holm) uses this affront to unite the tribes in Jihad, and attacks the tiny Legion garrison at the dig. An epic battle follows, very reminiscent of the film "Zulu". Costumes, firearms, and props are all very authentic-looking, and show great attention to detail.

The priceless Blue Water sapphire is coveted by the heirs of Sir Hector Geste - his new wife, Flavia; his daughter, Isabel; and his adopted twin sons, heroic Beau and pathetic Digby. When Sir Hector takes to his deathbed (where he remains for the duration of the film), Beau absconds with the stone, to keep it from his stepmother. Flavia pursues him to North Africa, dispensing sexual favors to promote her schemes.

Bertram Oliphant West (also known as Bo West) wants to clear his unjustly smeared reputation. He joins the Foreign Legion, with Simpson his manservant in tow. But the fort they get posted to is full of eccentric legionnaires, and there is trouble brewing with the locals too. Unbeknown to Bo, his lady love has followed him in disguise...