Two petty gangsters trying to elude their enemies join the French Foreign Legion.
The suave Dan Linton and his unrefined partner, Spike Conover, are two American ex-racketeers hiding from their enemies in Paris. At a cafe, they charm Louise, the wife of Henri Rillette, and her sister Yvonne Cartier. When the gangsters claim that they are businessmen seeking "peace and quiet," Yvonne jokingly suggests that they go to Morocco and join the Foreign Legion. Dan and Spike abruptly flee when they spot Al Perrelli, a rival gangster who appears to be carrying a machine gun, and soon after, they decide to join the legion, thinking their lives will be less stressful. On the train, they again encounter Henri, who has been transferred to Morocco, and, unaware that he is a captain in the legion and their superior officer, make mischief that results in Henri being dragged out of the dining car by train employees. In Morocco, Henri orders one of his men, Sergeant Groebner, to consider Dan and Spike under arrest during their training and not to spare necessary disciplinary measures. Meanwhile, unknown to Henri, Arab brigands led by Sheik Abdul-Ben-Abou and his subordinate Ali smuggle arms into the area, using Henri's car. Some time later, Dan and Spike are ordered into town on an errand and encounter Honey Evans, an American cabaret dancer to whom they are both attracted and with whom they shirk duties and get drunk. Spike's inconvenient habit of throwing empty bottles over his shoulders causes disorder in the bar, and when Henri discovers them, Dan and Spike are placed under arrest and soon after told they will be transferred to an outpost that is under attack. Believing that the transfer came about because Groebner, who is attracted to Honey, wants no romantic rivals, Dan and Spike hold the sergeant at gunpoint and bribe him to assign them "soft jobs" with the offer of monthly payments until their terms of enlistment are complete. Soon after, Dan is ordered to escort Yvonne on a horseback ride. Although they enjoy each other's company, as the outing ends, they barely escape an ambush by Abdul-Ben-Abdou's men. Later, Spike enjoys a rendezvous with Honey, until Dan attempts to cut in, and Groebner unexpectedly appears. An argument commences, which is overheard by Henri, who learns about the bribe, and arranges for all three men to be transferred to his next assignment location. While at their punishment assignment, El Gazar, Dan and Spike are able to avert the kidnapping of Yvonne, Louise and the general's wife, whom Abdul-Ben-Abdou tries to take as hostages. However, because of past misconduct and various other infractions, the general sentences Dan and Spike to six months of hard labor at a disciplinary camp run by Adjutant Cartellini. When Cartellini, a cruel taskmaster supposed by the prisoners to have gone insane, causes the death of one of the prisoners, Dan attempts to stand up to him. Cartellini is poised to torture Dan in retaliation until Spike initiates a riot, which is interrupted by Abdul-Ben-Abdou's men surrounding the camp and fatally shooting the adjutant. Meanwhile, Yvonne and Louise, who were grateful to Dan and Spike for their rescue, had convinced Henri to bring them to the work camp for a visit, so that they, too, were trapped at the camp when the Arabs attacked. An exchange of gunfire between the Legionnaires and the Arabs results in a stalemate and, although Henri is able to contact his post to tell them of their emergency, he knows that aid cannot arrive until the next morning. During the night, the Arabs secretly plant a canteen filled with nitroglycerin dangerously near the besieged prisoners. Later, finding that the camp's water supply has been destroyed, Dan and Spike sneak out to retrieve the canteens of dead Arabs. When a sip from one canteen tastes foul, Spike, who is unaware of its lethal contents, pitches it in the direction of the enemy, inadvertently causing an explosion. By the time help arrives, the legionnaires already have attained victory over their enemies. As a reward, Henri arranges for a revoke of Dan's and Spike's sentences and promotes each of them to the rank of corporal. Finally, Dan and Yvonne make plans to see more of each other.