In 1910, astronomer John T. Carter arrives in the quiet New England fishing village of Illsmouth just as a celestial phenomenon—the return of Halley's comet—seems to trigger something sinister beneath the town's peaceful facade. Locals speak in hushed, fearful tones of ancient rituals performed in a hidden forest shrine, whispers suggesting a connection between the comet's arrival and the awakening of primordial entities that once ruled the land in darkness. Carter must unravel the village's cryptic history and confront the supernatural forces driving its inhabitants toward madness and ritual, navigating both the mundane mysteries of the present and the terrifying secrets buried in Illsmouth's past. What begins as a routine stargazing expedition becomes an investigation into whether the comet's return has truly unleashed an otherworldly curse upon this isolated community.