A mysterious young man bearing strange scarifications and found wandering at the gates of Paris is hospitalized at the Saint-Maurice Hospital and disappears under unusual circumstances. A notebook in which he recorded his writings tells us his strange story, which begins with his initiation into a Freemasonic lodge. He relates to a brother his tormented family history and shares his suspicions surrounding the long-ago disappearance of his father, whom he never knew. He imagines that his grandmother, a tyrannical and treacherous woman, is behind this disappearance, which has never been solved. He decides to investigate in his hometown, where he has never returned and whose name he refuses to even mention, as it evokes painful memories and arouses irrational anxieties. His investigation will lead him to unexpected discoveries on the borders of fantasy and madness. What is this dark force that he unleashed in spite of himself?