A young ecologically minded pseudo-intellectual Parisian, Orphée has just sold his computer service company. Opting for a nomadic lifestyle, he hitchhikes to a small provincial town called Moussin, where he deciides to set up camp for a few days. During his stay, Orphée becomes not only a key witness and investigator, but also the Numner One suspect in a series of mysterious, highly spectacular murders that are striking down well-known figures in local medical and pharmaceutical circles. With the help of a young woman, a pharmacist from the area Orphée gets to the heart of the matter before making a quiet exit, going on to further adventures...