En route to Italy, a group of American tourists learn of a series of DIY travel guides, nicknamed "The Book". These unofficial guides are collected and updated with first-hand experiences by the travelers themselves. Different "Books" scatter the continent, telling of the best lodging, deals, and "off the grid" adventures from sight seeing to local folklore for anyone clever enough to find them. A local cult, practitioners of Sanctus Letum, the Holy Death, disrupts the American's plans for adventure when they hide pages from the Dark Book, Shaitan, in one of the travel guides. The friends are lead down a path of secret religion, death, resurrection, and demonology.