Nor was it comforting when her mother began disappearing into the manor’s cellar and emerging with the reek of sulfur on her, muttering to herself in strange languages. When she did talk to Grace, it was mostly on the topic of the treachery and ill-intent of the Nephilim. These lectures would start and stop seemingly at random, picking up in the middle of a thought as though the days since the previous talk hadn’t passed at all, and this was all one long continuous lesson.

Grace hadn’t thought anything evil of the Shadowhunters as a whole—she had lived among them for her first years of life, after all—but Tatiana illustrated her lessons well, delving into the dark corners of Blackthorn Manor and finding all manner of gruesome history there. In a dusty chest in the cellar, a collection of Downworlder spoils—vampire teeth, a desiccated preserved werewolf paw, what seemed to be an oversize moth’s wing floating in a clear, viscous liquid. These spoils had been illegal to take for the past thirty years, Tatiana admitted, but for the nine hundred years of Shadowhunter history prior to that, they were common. A diary entry, detailing the stripping of the Marks of someone’s insubordinate youngest son. “ ‘They threw him into the road,’ ” Tatiana read aloud, “ ‘for the good of the family and Clave.’ ”

The pièce de résistance of her collection, hidden in the study at Chiswick Manor, was an aletheia crystal, a faceted stone, enchanted to preserve a person’s memories. Grace would have thought that families would use such magic to record joyful events, but this one contained a short, grisly scene in which one Annabel Blackthorn, who had lived a hundred years ago, was tortured by the Inquisitor for consorting with a Downworlder and sentenced to be exiled to the Adamant Citadel.

“These are the Nephilim,” Tatiana said, “these are the ones who seek to destroy us. These are the ones who killed our Jesse.”

She broke down then, sobbing and collapsing onto the floor, and Grace snuck away to bed once she realized her mother would demand no more of her that evening. But though Grace closed her eyes, the image of the long-ago Blackthorn girl stayed in her mind for many hours. Her helplessness. Her terror. She had made one decision for herself, Annabel, and for it she lost everything. Grace wondered, then, whether her mother had intended a somewhat different lesson than the one she’d given.