Belkacem, a young unemployed man living in the Saharan village of Boulhilet, is entrusted by Bouacha, an old dervish who came from nowhere, with the secret of the olive tree, the only lush tree and true mystery in this stone desert. After water supply works, modern life bursts into the village. Belkacem, ill-prepared for this situation, confuses dream and reality. Believing he has killed his rival who loves his beloved, he flees the village after donning the clothes of the dervish, whose gait he now imitates.