Dexter Morgan isn't exactly the kind of man you'd bring home to your mum. At heart, he's the perfect gentleman - he is supportive of his sister Deb, a Miami cop; he has a shy girlfriend and is liked by her young son. In fact, Dex seems to lead a quiet, normal life bordering on the mundane. Despite the fact that he can't stand the sight of blood, he works as a blood-spatter analyst for the Miami police.
But Dexter also has a secret hobby: he is an accomplished serial killer. So far, he's killed 36 people and has never been caught because he knows exactly how to hide the evidence. And while that may lead some people to assume he's not such a nice guy - he tempers his insatiable hunger for brutality by only killing the bad guys.
However, Dexter's well-organised life is suddenly disrupted when a second, much more visible serial killer appears in Miami.