When eight-year-old Kathy Stone turns up on the side of the road a year after her abduction, the world awaits her harrowing story. But she doesn’t speak at all, not even to her own parents. Child therapist Robin Hart is the only one who’s had success connecting with the girl. Robin has been using play therapy to help Kathy process her memories. But as their work continues, Kathy’s playtime takes a grim turn: a doll stabs another doll, a tiny figurine is chained to a plastic toy couch. All of these horrifying moments, enacted within a Victorian doll house. Every session, another toy dies. But the most disturbing detail? Kathy seems to be playacting real unsolved murders. Soon Robin wonders if Kathy not only holds the key to the murders of the past but if she knows something about the murders of the future.

An online video of a girl clawing at the ceiling of her own grave could be the worst thing FBI forensic psychologist Zoe Bentley has ever seen. Perhaps even more disturbing is the implication of the video’s title: “Experiment Number One.” Zoe and her partner, Special Agent Tatum Gray, work as fast as they can to find the monster behind the shocking video, but soon another one shows up online, and another girl turns up dead. Meanwhile, a different murderer is on Zoe’s mind. Rod Glover has been tormenting her since childhood, and his latest attack is a threatening photo of himself with Zoe’s sister. As Glover’s threats creep toward action, Zoe is torn between family and duty.

Three Chicago women have been found strangled, embalmed and posed as if still alive. Doubting the findings of the local PD’s profiler, the FBI calls on forensic psychologist Zoe Bentley to investigate. Zoe quickly gets off on the wrong foot with her new partner, Special Agent Tatum Gray. Zoe is a hunter, intense and focused; Tatum is a smug maverick with little respect for the rules. Together, they must descend into a serial killer’s psyche and untangle his twisted fantasies, or more women will die. But when the contents of three inconspicuous envelopes reveal a chilling connection to gruesome murders from Zoe’s childhood, suddenly the hunter becomes the hunted.