JD's relationship with a comely social worker makes Elliot both jealous, and suspicious, Turk discovers that Dr Cox has a thing for Carla.
Cal is left reeling when a seemingly innocent man he helped convict is executed. In a plot that springs surprises, he finds out if he has blood on his hands.
When a religious cult operating in Canada unearths a spacecraft similar to the one Scully discovered in Africa, a plot is set in motion to kill baby William.