A newly acquired obsidian mirror in the Tuileries Palace reflects not the viewer but a grotesque, distorted version of their soul. Soon, members of the court begin succumbing to madness and committing unspeakable acts, seemingly possessed by the reflected entities. Dupin is summoned by a desperate King Charles X to investigate the mirror's origins, uncovering a history of dark magic, forbidden rituals, and a haunting tale of a queen consumed by vanity and summoned a demonic force.

A renowned clockmaker confesses to Dupin that he is being driven mad by the relentless ticking of a grandfather clock, a sound he believes is the amplified heartbeat of his deceased wife, whom he may have accidentally poisoned. Dupin investigates, discovering a complex series of intricate mechanisms and hidden chambers within the clock, revealing not guilt, but a desperate attempt by the clockmaker to preserve his wife's memory through a bizarre, almost alchemical, process that has inadvertently unleashed a spectral presence.