In the early morning, in the mountains, a car rolls at a normal pace on a straight and obstacle-free road. Yet brutally, she swerved, followed by several barrels, before immobilizing. The passenger, Pierrot Clément, owner of an altitude restaurant above Lusagne, dies on the job. Present at the scene, a witness thought he saw a white form inside the vehicle, which then disappeared. Alex Hugo discovers that another appearance of the "White Lady" took place in the same place, a few years before, just before another drama...