When DCI Adam Bishop arrives at the crime scene in the dead of night, the sight of the body is bad enough. But what Adam notices next chills him to his core. More bodies surface. And the spray-painted numbers daubed above the corpses reveal the horrific truth: the killer is counting down. But to what end? Adam has no idea, until Dr. Romilly Cole knocks on his door with damning evidence pointing to a series of murders 25 years earlier --- a case she knows intimately from her past. Now it’s personal --- and the next knock on his door could be fatal.

Detectives Cara Elliott and Noah Deakin are on the case of a series of seemingly unconnected murders, each different in method, but each shocking and brutal. As the body count increases, they can’t ignore the details that echo famous cases of the past --- Manson, Kemper, Dahmer and more. As Elliott and Deakin get closer to unmasking the killer, the murders are moving closer to home. Meanwhile, Jessica Ambrose is on the run. She’s been implicated as the arsonist who killed her neglectful husband and injured her young daughter. With the help of disgraced and suspended detective Nate Griffin, Jess discovers a shocking link between her case and that of the ultimate copycat killer working on his horrifying masterpiece.