Karl is called up to Seattle where he is reunited with twisted serial killer Tommy Cummins; Cassandra deals with council conflicts and an unexpected visit from her mother while the police squad struggles when one of their own is missing.

Karl and the police force investigate the murder of a man found dead at the bottom of his staircase. During their investigation, Karl's team discovers an item at the scene of the crime that may be linked to other murders. Karl warns Cassandra to stay out of the case, but her connection to it makes her unable to stop.