Professor Theo Cray is trained to see patterns where others see chaos. So when mutilated bodies found deep in the Montana woods leave the cops searching blindly for clues, Theo sees something they missed. Something unnatural. Something only he can stop. As a computational biologist, Theo is more familiar with digital code and microbes than the dark arts of forensic sleuthing.

Professor Theo Cray caught one of the most prolific serial killers in history using revolutionary scientific methods. Cut off from university research because of the shroud of suspicion around him after the death of his former student and the aftermath of catching his quarry, Cray tries to rebuild his life but finds himself drawn into another unsolved case. The desperate father of a missing child, ignored by the authorities and abandoned by his community, turns to Theo for help.

Computational biologist and serial-killer hunter Dr. Theo Cray receives an off-the-record request from the FBI to investigate an inexplicable double homicide. It happened at the excavation site where a murderer had buried his victims’ remains. In custody is a forensic technician in shock, with no history of aggression. He doesn’t remember a thing. His colleagues don’t even recognize the man they thought they knew. But an MRI reveals something peculiar. And abnormal.

Dr. Theo Cray has a legendary mathematical knack for catching serial killers. Until his exposure to a mind-altering pathogen knocks him off his game. It has upended an investigation, destroyed his reputation, and left him to question his own sanity. One person still trusts him to finish the job. His former professor Amanda Paulson is helping point Cray down a logical path to his prey: a nomadic health-care worker whose murder spree stretches back decades and whose victims number in the hundreds.