In his bid to unite all local tribes against the French colonial rules, a North African leader organizes an attack against Fort Algiers. After taking the fort from the French Foreign Legion troops, Amir and his sidekick Yussouf, order their men to kill all Legionnaires and maintain total secrecy. In Paris, French intelligence agent Yvette Del Mar is persuaded by her superiors to return to North Africa and pose as a nightclub singer. Her task is to entertain and ingratiate herself with the Amir in order to extract secret information from him. In Algiers, dismissed French Army officer Jeff Brown volunteers for the French Foreign Legion. Jeff is surprised to see his former girlfriend, Yvette, singing in the nightclub and he doesn't suspect the fact she is working for the French Intelligence. A romantic rivalry of sorts develops between Jeff and the Amir, over Yvette's favors. Later, a French spy is uncovered by the Amir and killed. Jeff is asked to replace the dead spy, due to his knowledge of Arabic and army signals. He agrees, not knowing that Yvette is snooping around the Amir's palace, as his guest. Unfortunately, Yvette is unmasked by the Amir and captured. Jeff somehow must enter the Amir's palace to rescue Yvette. At the same time, the Amir is planning a major attack on the French oil-fields. Jeff intends to rescue Yvette and return to base to warn the Legion about the imminent Arab attack.