A respected surgeon and rare-book collector is brutally murdered in his elegant Manhattan home, just hours after showing a book dealer the fifteenth-century manual of black magic—a grimoire—he'd received from a grateful patient. Now the doctor's blood is everywhere, and only the priceless grimoire is missing.

The horrific death of her beloved father has shattered Beatrice O'Connell's quiet, sane, and orderly world. Only by tracking down the vanished malevolent tome—with its dark spells and salacious illustrations—can she hope to put things right. But the search is leading Beatrice, her ex-husband, and a mysterious occultist into an expanding labyrinth of powerful evils, a tangled web that reaches as far as the Vatican itself. What coveted secrets are hidden in the missing volume that threaten to turn Beatrice into precisely what her unseen and unrelenting enemies are determined to destroy?