It is 1919 and the Great War has come to a close. But in the shadows of the world’s major cities, the killing has just begun. In this perilous time, as the division between order and chaos grows increasingly slim, a select group of visionaries have taken it upon themselves to ensure the safety of humanity. They are known as the Arcanum.

In London’s stormy Hyde Park, Konstantin Duvall, the Arcanum’s founder, has been killed in a suspicious accident. Dismayed, the group’s longest-lived member, Sir Arthur Conan Doyle, determines to avenge Duvall’s death-and uncover the secret left in his wake. For the dead man possessed the world’s most powerful-now missing-artifact: the Book of Enoch, the chronicle of God’s mistakes, within whose pages lie the seeds for the end of everything.

From the scene of the crime, Conan Doyle embarks on a path that leads him to the sleazy underworld of New York City’s Bowery and a series of deceptively disparate-but decidedly connected-murders. And as he calls upon the scattered members of the Arcanum for aid, he also finds himself embroiled in a story of war as old as time itself. Not of a struggle between countries, but between darkness and light. Peopled with the twentieth century’s most famous-and infamous-figures, here is an extraordinary tale in which the stakes go beyond the realm of humankind-into the divine.