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