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...

Lusagne, late afternoon. The children of the summer camp are returning from a mountain excursion, but Justine, 10, is missing the call. Her instructor, Marianne Helme, who was looking for her, did not come home either. Alex and Angelo mobilize volunteers and discover with fright the body of Marianne, stranded in a torrent, but no trace of Justine. Very soon, the suspicions are about Jeremy Veal, a retarded, light mental, who survives through odd jobs. is led under good escort to the rural police station, before which already camp residents claiming justice...