In Lebanon, industrialist Hennequin, director of a French oil company, entrusts engineers Jean Domèvre, a Frenchman, and Mokhrir, a Lebanese, with the prospecting of an isolated region granted to him by Countess Athelstane Orloff. Their search remains fruitless until Mokhir reports the discovery of a uranium deposit, but disappears before Jean can identify the location. He goes to the Countess for help in finding Mokhir and surprises her when, due to financial difficulties, she is negotiating her concession with the Englishman Hobson, director of a rival company. Attracted by Jean, the Countess nevertheless gives him her preference and they set off together in search of Mokhir.