During the day, Dexter Morgan is a jovial employee in the Miami Metropolitan Police Depoartment'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 bloodlust at night by carefully killing the serial killers he tracks down during the day. Based on the novels (Darkly Dreaming Dexter, Dearly Devoted Dexter and Dexter in the Dark) by Jeff Lindsay.
