Rare book dealer and lapsed novelist Lily Albrecht is minding her own business at a rare book sale in Manhattan when she’s approached out of the blue by an oddball colleague with a too-good-to-be-true offer: find a copy of an obscure 17th-century book of sex magic, The Book of the Most Precious Substance, and he’ll come through with a client willing to pay a million dollars. Having never read a Sara Gran novel, Lily says sure. Within hours, the other dealer is dead under mysterious circumstances.
Not to be deterred, ever-pragmatic—and broke—Lily decides to track down the book and the client on her own, with the help of Lucas, a charismatic fellow dealer who may or may not be on her side. Lily soon finds out that the Book is more than just a priceless curio; its promise of earth-shattering sex and limitless power for aspirants who complete each of its five rituals is real, and there’s more than one obscenely wealthy and correspondingly ruthless person who’s after it.