Miami, 1991. When his bloodthirsty urges can't be ignored any longer, young Dexter Morgan must learn to channel his inner darkness as he transitions from student to avenging serial killer with the guidance of his father, Harry.

In 1991, young Dexter Morgan (Patrick Gibson) begins his internship as a forensic technician for the Miami Metro Police Department while transitioning into an avenging serial killer. When his bloodthirsty urges can no longer be ignored, Dexter must control his inner darkness. With the help from his foster father Harry (Christian Slater), he adopts the Code designed to help him find and kill other serial killers while staying under the radar of law enforcement.