In Miami, the orphan Dexter is raised by detective Harry Morgan, who discovers that his foster son has the urge to kill. Harry directs the impulse of the boy to kill bad people, teaching him how to operate without leaving any trace. After Harry's death, Dexter works in the forensic department of the Miami Police Department, where his step sister, Debra, works in the Vice and Narcotics Unit. During his free nights, Dexter leads a double-life, chasing and killing murderers and collecting samples of their blood, or dating Rita Bennett. After executing a pedophile and a rapist (who have killed their victims), Dexter investigates an intriguing serial killer that drains the blood and freezes the severed bodies of his victims.