We are not alone. Some call them devils or demons. But they are real. They are down there. And they are waiting for us to find them.
In a cave in the Himalayas, a guide discovers a self-mutilated body with a warning: Satan exists. In the Kalahari Desert, a nun unearths evidence of a proto-human species and a deity called Older-than-Old. In Bosnia, something has been feeding upon the dead in a mass grave. So begins mankind’s most shocking realization: the underworld is a vast geological labyrinth populated by another race of beings.