After the team discovers that suspect Paul may not be who he says he is, and was involved in an infamous murder in the past, the investigation revisits the 15-year-old case. Wounds are re-opened for the family of the victim as Paul's psychopathic accomplice in the historical murder is visited in the hope that he can shed light on the current investigation.

Further victims are killed and a distinctive, sadistic modus operandi begins to become clear. The team turns to forensic psychologist Sasha for advice on the killer, but her proximity to the suspects puts her viewpoint in doubt.

As the team move closer to discovering who the killer is, they question whether a murderer can truly be rehabilitated and what that rehabilitation really means. Show less