Kerry Barker

A killer targets survivors of a high-school massacre, who have gathered for a reunion; Hotch fears that his son is being bullied.

Detective Slaughter returns to enlist Castle's help in solving a high-stakes robbery case. But when a body is found linked to the crime, Slaughter becomes the number one suspect in the heist turned murder, while Castle has to determine whether he's guilty or help to prove he's innocent.