In 1991 Miami, Dexter Morgan evolves from a student into a vigilante serial killer. As his insatiable desire for blood becomes impossible to suppress, Dexter is compelled to harness his inner darkness. Under the mentorship of his father, Harry, he embraces a Code that aids him in identifying and eliminating those who pose a threat to society, all while avoiding detection by law enforcement. This proves to be a unique challenge for the young Dexter, especially as he starts a forensics internship at the Miami Metro Police Department.