Based loosely on novels by author Jeff Lindsay, Dexter follows the life of Dexter Morgan (Michael C. Hall), a charismatic blood spatter analyst who works in the forensics at the Miami Metro Police Department. On the outside, Dexter seems like the perfect guy -- he has a sister, Debra (Jennifer Carpenter), that adores him and a steady girlfriend, Rita (Julie Benz), with two kids that look up to him. However, what they don't know is that Dexter moonlights as a serial killer, only he isn't your typical killer. Basing his life on the teachings of his foster father, Dexter only kills people who truly deserve it: he ensures that those who got away with horrible crimes will never kill again.

The show summary is provided by TVRage.