I recommend this show to everyone.
Taken from IMDb: During the day, Dexter Morgan is a jovial employee in the Miami Metropolitan Police Department`s crime lab, but his meticulously crafted life masks his true nature. In reality Dexter is a disciplined and murderous psychopath (a self-admitted "monster"), and he slakes his blood lust at night by carefully killing the serial killers he tracks down during the day.
(CBS started airing its edited version last month but its not the same.)