Two twin brothers have joined the army, Paul by vocation is a lieutenant of spahis and Georges to escape the police is a sergeant in the Foreign Legion. A snitch having informed the police of Georges' presence at the Legion, he must leave. In Casablanca, Paul helps his brother escape the police by taking his identity to allow him to regain his honor.

A respected gangster, Justin, finds himself in a deadly feud with his rival, the unscrupulous Esposito. The latter plans to steal a cargo of opium bound for China and to have Justin killed.

Toward the close of World War I, European railroads in Djibouti are under siege by bands of indigenous warriors, while one of the white employees falls for a mysterious woman tied to the rebels.