The night in the city always hides secrets that you can't imagine. Dexter Morgan (Michael C. Hall) is a hard-working forensic doctor. He is kind, humorous, and popular. He has a free and easy, boyish sister Debra (Jennifer Carpenter), and a gentle and beautiful girlfriend Rita (Julie Benz). Being in the police system, Dexter is able to fully hide his secret identity as a cold-blooded killer, and use his position to find the most heinous people who have escaped legal sanctions. Outside the law, the real villains deserve their punishment. Dexter chose such a dangerous identity because of his painful experience when he was three years old. His mother was dismembered in front of him. The villain left, and he and his brother were thrown in a pool of blood for three days before being discovered. Dexter was meticulous and skillful in carrying out secret murders until his brother Brady, who had been sent to a mental hospital, suddenly appeared in his life.