Each day, inhabitants of a small community in the French Alps find another of their ewes with its throat cut. When one of the villagers too is killed people begin to wonder: could it be the work of a werewolf? Soon suspicion falls on Massart, one of the villagers, because of his beardlessness (according to popular legend, werewolves have no hair on their bodies because they are inside the body).
Soliman, the victim's adopted son; Le Veilleur, a lonely sheperd and Camille, a lovely girl from the city, decide to pursue Massart and their hunt leads them into the Alps, but their incompetence is undisguisable and they decide to summon Commissaire Adamsberg — well known for his peculiar investigation methods — to help. Thanks to his extraordinary intuition, Adamsberg unearths an astonishing truth, one that the villagers are going to find hard to believe