Detective Catherine Jensen teams with college professor Thomas Schaeffer to catch a serial killer. Both have troubled histories, and, although brilliant, their flaws may outweigh the positives as they try to track down the killer before he strikes again.

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

Catherine is forced go to Howard 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. Catherine takes Thomas to the scene of her childhood trauma where she finally reveals all the details that still haunt her.

Catherine dives into a new case to distract herself from the revelation she heard from Thomas regarding her mother's knowledge. Meanwhile, Thomas ventures too deeply into the mind of a killer.

Catherine takes on a unlikely role when she looks at Thomas' profile and the killer strikes another family.

Thomas becomes obsessed about an ominous letter that puts his career and family in serious jeopardy. Catherine works to overcome a personal loss.

Thomas and Bisgaard try to keep Catherine calm after Molbeck is attacked; Catherine and Thomas face their greatest foes.