Casbah is a musical remake of the 1938 film Algiers, which was in turn an American English-language remake of the 1936 French film Pépé le Moko. The plot, which follows that of the 1938 film rather faithfully, deals with Pépé le Moko (Tony Martin), who leads a gang of jewel thieves in the Casbah of Algiers, where he has exiled himself to escape imprisonment in his native France. Inez (Yvonne De Carlo), his girl friend, is infuriated when Pépé flirts with Gaby (Marta Toren), a French visitor, but Pépé tells her to mind her own business. Detective Slimane (Peter Lorre) is trying to lure Pépé out of the Casbah so he can be jailed. Against Slimane's advice, Police Chief Louvain (Thomas Gomez) captures Pépé in a dragnet, but his followers free him. Inez realizes that Pépé has fallen in love with Gaby and intends to follow her to Europe. Slimane knows the same and uses her as the bait to lure Pépé out of the Casbah.