It's business as usual for Tavish McCaskill, a Canadian bookseller living in Geneva, until a strange customer comes to his shop with an even stranger book: an old Kabbalistic manuscript by a legendary rabbi that's supposedly been kept secret for five hundred years. At first, Tavish thinks it must be a forgery: why else would it include quantum equations that hadn't been developed until the 20th century? But closing this matter isn't as simple as closing a book—and Tavish's customer isn't the only person who's interested in this one.

Soon, Tavish is walking the ancient Pilgrim's path through Switzerland, trying to unravel the mysteries of the manuscript while running for his life. As he surrenders himself to the twists and turns of fate and of the path, Tavish grapples with the loss of his daughter, his strained relationship with his ex-wife, new acquaintances who flicker between friend and foe, and the intoxicating possibility that this Kabbalist text could hold the answers to it all.