When a massive explosion at a top-secret prison known as the Pit allows notorious serial killer Richard Harris to escape, disgraced FBI agent Bex Henderson is called back into action to hunt him down before he kills again.

Dr. Ezekiel Malak, a hospital psychiatrist turned serial killer, is prowling for new victims in Chicago. Bex and the team work to find a method to his madness in a desperate bid to get ahead of him until Malak makes a move no one saw coming.

Bex and the team race to catch Mark Marsden, known as the Widower, a handsome and charming serial killer who murdered three of his wives in cold blood. Everything changes when Mark decides to take a new bride.

Bex and the team track the brilliant and beguiling Jenna Wells, the notorious Killer Chemist whose therapy in the Pit has made her even more dangerous and deranged.