The highly anticipated new thriller from internationally renowned author Sara Gran, author of Come Closer and the Claire DeWitt series.

"Gran's writing, like the grimoire, is palpably seductive. The search for pleasure and magic is an aphrodisiac, one that pulses on the page." - Danielle Trussoni, The New York Times

"Gran perfectly captures the eccentric world of antiquarian bookselling while portraying a profound and magical reckoning with loss and the possibility of going on. She has outdone herself. " - Publisher's Weekly, Starred Review

"While Lily's hunt propels the story forward, it is Gran's frequently exquisite prose that demands investment from its audience." - Bookpage, Starred Review

"Sara Gran's THE BOOK OF THE MOST PRECIOUS SUBSTANCE is a mix of book buying mystery, erotica, and a pinch of Clive Barkerian obsessive existential horror, but it's all Gran. And it's all brilliant." - Paul Tremblay, author of The Cabin at the End of the World

"Extravagant, sexy and compelling. I loved it." - Lauren Beukes, author of The Shining Girls

"There's two types of magic at play, here. There's what these characters are trying to do, mixing books and sex and spells, and then there's the magic Sara Gran is doing to us, as we compulsively read this literary thriller. And there's a third magic we only wish we could do: pay in blood to go back, read this book again for the first time." - Stephen Graham Jones

A mysterious book that promises unlimited power and unrivaled sexual pleasure. A down-on-her-luck book dealer hoping for the sale of a lifetime. And a twist so shocking, no one will come out unscathed.

After a tragedy too painful to bear, former novelist Lily Albrecht has resigned herself to a dull, sexless life as a rare book dealer. Until she gets a lead on a book that just might turn everything around. The Book of the Most Precious Substance is a 17th century manual on sex magic, rumored to be the most powerful occult book ever written--if it really exists at all. And some of the wealthiest people in the world are willing to pay Lily a fortune to find it-if she can. Her search for the book takes her from New York to New Orleans to Munich to Paris, searching the dark corners of power where the world's wealthiest people use black magic to fulfill their desires. Will Lily fulfill her own desires, and join them? Or will she lose it all searching for a ghost? The Book of the Most Precious Substance is an addictive erotic thriller about the lengths we'll go to get what we need-and what we want.