Those Who Kill

When murders are not grounded in traditional motives and patterns of behavior, it takes a very particular kind of person to catch the serial killer; someone who knows and understands the killer's dark side and the fantasies that plague him.

While Catherine waits to be cleared for duty by the D.A.'s office, and Thomas secretly investigates Catherine's past, a brutal murder and a John Doe suicide are discovered.

As the killer escalates, Catherine uses the investigation of the two victims to push Thomas to research her allegations further.

Catherine is forced go to Ray for more information on the case, while Thomas has a real conversation with John about getting inside the minds of murderers. Using Thomas' narrowing profile, Catherine closes in on the killer.

Thomas' decision to stop working on active cases causes Catherine to investigate his past, leading her to an unexpected family history.

Reeling from Thomas' revelation about Marie, Catherine throws herself into investigating a family annihilator. Meanwhile, Thomas struggles with his past demons resurfacing.

As the killer invades another family, Catherine questions the cost of her vendetta. Thomas' profile causes Catherine to take on an unlikely role.

Thomas obsesses over an ominous letter that puts his career and family in jeopardy, while Catherine attempts to put the past behind her after a sudden personal loss.

Thomas tries to keep Catherine under control after the death of her mother proves too difficult for her to handle. A sadistic killer continues to abduct couples.

After Catherine abandons Molbeck to be attacked by the killer, Thomas and Bisgaard struggle to keep her from going off the rails. Catherine and Thomas face their greatest foes.