This was the first series I committed to watching on ShowTime. It turns out that ShowTime (owned by CBS) is a pretty good cable channel.
When I describe this to people, they must wonder about me... Dexter is a serial killer who works for the Miami Police CSI Unit. The series tells the story in three time periods -- when Dexter was a young boy, when he was a teenager and now, when he is in his late 20's early 30's.
When he was a young boy, his father Harry, a Miami police officer who had adopted him, recognized certain traits relating to killing animals that he understood were the precursors of the profiles of serial killers. Harry worked to instill into Dexter a code of behavior so that Dexter could channel his obsession to result in as little harm as possible.
As a result, Dexter has become a Blood Spatter expert for the Miami CSI for his day job. In his spare time, he pursues his avocations by making sure that criminals he encounters in his day job who might otherwise escape capture and punishment do not get away... Thus the channeling his obsession to do good (for some value of good...).
Of course he is always vulnerable to getting caught so this adds to the suspense. In addition, there are several other suspense generating mechanisms in play.
Once you get by the blood, this is an excellent television series. There have been two seasons which you can still see and there is another season planned for the future.
Finally, here is an interview with the author, Jeff Lindsay.