Rare book dealer Lily Albrecht has been given a tip-off about The Book of the Most Precious Substance, rumoured to be the most powerful occult book ever written. With some of the world's wealthiest people willing to pay a fortune for it, she embarks on a journey from New York to New Orleans to Munich to Paris, knowing that it could also help erase the greatest tragedy of her life.

But does the book really exist at all, or will Lily lose everything in search of a ghost?