Pepe le Moko (Jean Gabin) is a well-known criminal mastermind who eludes the French police by hiding in the Casbah section of Algiers. He knows he is safe in this labyrinthine netherworld, where he is surrounded by his fellow thieves and cutthroats.
Police inspector Slimane (Lucas Gridoux), who has developed a grudging respect for Pepe, bides his time, waiting for Pepe to try to leave the Casbah. When Gaby Gould (Mirielle Balin), a Parisian tourist, falls in love with Pepe, the inspector hopes to use this relationship to his advantage.
He tells Gaby that Pepe has been killed, knowing that the heartbroken girl will return to Paris -- and that Pepe will risk everything to go after her.
The French Pepe le Moko was remade in the US as Algiers, which followed the original so slavishly (except for changing its ending) that the American producers were able to utilize generous amounts of stock footage from the French film.