Halstead’s past resurfaces when a former Army colleague is implicated in a deadly blast. As the FBI launches an investigation into Roy’s disappearance, Upton feels the pressure of the secret she and Voight are sharing.
The BAU is called to Oklahoma to investigate a murderous clown who is terrorizing a town.
Ducky is attacked by a man who claims to have information about his half-brother, who died decades earlier; Jake and Bishop talk about their future.