After the discovery of aluminum residue on a recent victim, Catherine scans crime scene photos to see a neighboring house under construction. The foreman gives them the name of a man recently fired for looking at the neighbors. The team visits his house to find his family dead and a home video they presume he watched after killing them. They learn the general area of his current target and are able to find the exact house. Inside, the killer has cut the mother, but she opens the door for Catherine and they switch places. Catherine assumes the wife and mother role, cooks breakfast, and gets the killer to sit in front of the window at the kitchen table. He is killed by a police sniper. The situation affects both Thomas and Catherine. He promises his family to never let a case take precedence over them, and Catherine messages her mother to talk about Howard.

The team investigates the connection the killer has with his drug dealing, as he targets his next couple. Meanwhile, Thomas becomes paranoid trying to think like him. At her mother's funeral reception, Catherine is introduced to a boy being mentored by Howard. Suspicious, she is torn between investigating him and the murder case. This causes her to abandon Molbeck on surveillance and he is shot by the killer.