In a cave in the Himalayas, a guide discovers a self-mutilated body with the 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" feeds upon the dead in mass graves. So begins mankind's shocking realization that the underworld is populated by another race of beings--and they are waiting to be found.