Olivia Prior, an orphan raised in a grim institution, receives a mysterious invitation to Gallant, a decaying ancestral estate. Upon arrival, she discovers the crumbling mansion harbors a sinister secret: a parallel world teeming with ghouls and a dark entity threatening her lineage. Schwab masterfully weaves a gothic tale of family secrets, belonging, and the terrifying allure of the unknown. Olivia must navigate the mysteries of Gallant and confront the darkness inextricably linked to her past and future, deciding where she truly belongs.