An intoxicating erotic thriller about what we’re willing to do to get what we need… and what we want. After a tragedy that turned her whole life upside down, former writer Lily Albrecht resigned herself to a dull, colorless existence as a seller of rare books—until she received an offer to find a book that could set everything right… “A Book About an Invaluable Substance” is a 17th-century guide to sexual magic, promising unlimited power and unparalleled sexual pleasure. If you believe the rumors, it’s the most powerful occult book in the world—and some of the rich are ready to pay a fortune to get it… unless it’s just an old legend. But can Lily fulfill her own desires? Or will she lose everything chasing a mirage? ___________________________________________ “Sara Gran’s prose—and the grimuar being hunted—are palpably seductive. The search for pleasure and magic is an aphrodisiac that pulses through the pages.” — Daniel Trossoni, best-selling author and New York Times literature columnist “A sensational occult thriller. Gran’s writing is unbelievably alluring—just like Lily Albrecht, readers have no choice but to follow the book to its ominous conclusion.” — New York Times “Sara Gran’s book is a blend of a shopping secret, eroticism, and a pinch of existential horror. And it’s absolutely fantastic.” — Paul Tremblay, author of the best-seller “The Cabin at the End of the World” “Extravagant, sexy, and irresistible. I loved it.” — Lauren Beukes