A monk deserts his calling to marry a beautiful woman he meets in the Sahara.

After the death of her invalid father, wealthy Domini Enfilden returns to Le Couvent de Ste. Cecile, where she was reared, to seek counsel from Mother Josephine about her loneliness. The Mother Superior tells her that in the solitude of the Sahara Desert, she might find herself. Meanwhile, at a Trappist monastery at el Lagarnine in Tunis in Northern Africa, a visitor, Captain de Trevignac, tastes the liqueur for which the monastery is famous. The liqueur is made from a secret formula by Brother Antoine, who has just fled the monastery, taking the secret with him. En route to the city of Beni Mora, Algeria, Domini meets Antoine on a train, but he is silent. Later, in a cafe, Antoine is entranced by an exotic dancer named Irena. When Irena pulls a knife on her lover, Hadj, who will not marry her, Antoine helps Domini flee, and introduces himself as Boris Androvsky. The next day, they ride to the Oasis of the city Azur, where they meet Count Ferdinand Anteoni, who tells Domini to wait to venture into the desert until the urge is very strong. When native girls admire the crucifix around Boris' neck, he gives it to them by casting it in the water. Although Boris attracts Domini, he shocks her by his violent antipathy to religion. Anteoni warns Domini, "a man who fears to acknowledge his God is unwise to set foot in the desert," and tells them that the Arabs have a saying that the desert is the garden of Allah. Later, a sand diviner tells Domini that something glorious is in store for her during her pilgrimage into the desert, but also gives her a grave warning. As the weeks pass, Domini and Boris fall in love, and Boris still keeps his past a secret. While out riding, they come to a church, as the seer foretold. There, Father J. Roubier, who promised Mother Superior he would look out for Domini, notices Boris' fear and anger toward the church. Although the priest warns Domini not to make friends with Boris, after Boris threatens to leave, he and Domini swear their love, and the priest agrees to marry them the next day. Following the wedding, Boris and Domini take a caravan into the desert with Domini's guide, Batouch, and Hadj. One night, Domini lights a torch to guide Boris back to the camp, and inadvertently saves a patrol that has been lost for three days. Among the men is de Trevignac. Boris returns and de Trevignac is sure they have met before. After Batouch serves a bottle of the Lagarnine liqueur, de Trevignac remembers who Boris is and leaves the table in anger. Domini, confused, pleads with Boris to tell her the truth, but he refuses. At dawn, Domini asks de Trevignac to tell her what happened between him and Boris, but he merely crosses himself and walks away. De Trevignac and his men depart, but he tells Anteoni where the caravan is camped. At dinner, Anteoni tells the story of the Lagarnine liqueur, which will never again be manufactured as the monk who knew the secret of the liqueur disappeared after taking his final vows. Domini is horrified by the story, but Boris asserts that the man had a right to love, then cries at the realization of what he has done. After Anteoni leaves, Boris falls on his knees in the sand and tells Domini about his life at the monastery, where he had lived since childhood under the vow of silence, and spoke with people for the first time when, as an adult he was put in charge of the monastery's hotel. Believing that no one who loves will be punished by God, Domini agrees to let Boris return to the monastery and make reparations, promising that they will be together forever. At the gates of the monastery, Boris and Domini embrace for the last time.