Dexter is finally forced to confront his greatest fear, as Debra witnesses his insatiable, ritualistic slaying of a killer. Now Deb knows the secret of his Dark Passenger, his undeniable thirst for blood, and the Code that their father Harry instilled in him as a young boy. But as Deb tries to reconcile the unfathomable idea that her beloved brother is Miami's most notorious serial killer, Dexter is still pulled by his natural impulses to seek out the guilty and exact his brand of justice.