The BAU investigates a group of suspects with a pack mentality who are randomly selecting their victims in the nation's capital and murdering them for the thrill of it.
Crowley notices Dean's increasing level of aggression; a vengeful man named Cole captures and tortures Sam.
Sam ignores Dean's directive and continues to search for a cure; a new murder case brings the brothers in contact with Cole -- who ends up being infected by a Khan worm that turns men into murderers.
A desperate father turned serial killer coerces the team into taking another look at his six-year-old son's 1987 rape and murder.
Jack and Vaughn are forced to ally themselves with Sloane in order to rescue Sydney from the NSC; Lauren must choose to side with the NSC or her husband.