Men and women are turning up dead in the outskirts of Seattle, poisoned by a mysterious chemical. When a pattern is discovered and it becomes clear that a twisted serial killer is on the hunt, the FBI calls in their best asset: Special Agent Riley Paige. Riley is urged to return to the line of duty - but Riley, still reeling from the attacks on her family, is loath to return. Yet as bodies mount, and the murders become more inexplicable, Riley knows she has no choice.

Women are turning up dead on a lone stretch of highway in Delaware. Some go missing for an inexplicable length of time, while others are turning up dead, their bodies left out for display in bizarre and mysterious ways. When a pattern is discovered, it becomes clear to the FBI that a twisted serial killer is on the hunt - luring girls in devious schemes - and that he won't stop killing, ever.

When Special Agent Riley Paige finally decides to take a well-needed rest from the FBI, a request for help comes from the most unlikely source - her own daughter. April's best friend is devastated by the death of her sister, a freshman at Georgetown. Worse, she is convinced that the suicide was staged, and that her sister was murdered at the hands of a serial killer.

When prostitutes turn up dead in Phoenix, not much attention is paid. But when a pattern of disturbing murders is discovered, the local police soon realize a serial killer is on a rampage and they are in way over their heads. Given the unique nature of the crimes, the FBI, called in, knows they will need their most brilliant mind to crack the case: Special Agent Riley Paige.

There is one cold case that has plagued Special Agent Riley Paige for her entire career, dwelling at the corners of her consciousness, forcing her to return to it again and again. The only case she has never solved, she has finally put it out of her mind. Until she gets a call from the murdered victim's mother. It spurs Riley to face the case once again, and to not give up until she has found answers. Yet Riley barely has time to catch her breath when she receives a lead for another cold case, one which, if possible, strikes an even deeper note within her.