Dexter is an American television drama series that airs on Showtime. It debuted on October 1, 2006, and filming has begun on the fifth season, due to begin airing on September 26, 2010. Set in Miami, the show centers on Dexter Morgan (Michael C. Hall), a blood spatter-pattern analyst for the Miami Metro Police Department, who moonlights as a serial killer. The show's first season was loosely based on the novel Darkly Dreaming Dexter by Jeff Lindsay, the first of his series of Dexter novels. Subsequent seasons have evolved independently of Lindsay's works. It was adapted for television by screenwriter James Manos, Jr., who wrote the pilot episode.
Dexter structures his killing around "The Code of Harry", a body of ethics and procedures devised by his adoptive father Harry (who was a Miami cop) to make sure Dexter never gets caught and ensure that Dexter kills only other killers. Harry also trained Dexter in how to interact convincingly with other people, despite being a psychopath, since the murder of his biological mother, Laura Moser, did in fact turn Dexter into a serial killer. As an adult, Dexter has largely escaped suspicion (with some exceptions) by being genial and generous and maintaining generally superficial relationships. However, his attachment to his sister Deb, his significant other Rita, his stepchildren and (later) his biological son have all complicated his duplicitous lifestyle while making him question his need to kill.
In February 2008, edited reruns began to air on CBS. The series has enjoyed wide critical acclaim and popularity. Season 4 aired its season finale on December 13, 2009 to a record-breaking audience of 2.6 million viewers, making it the most-watched original series episode ever on Showtime. Michael C. Hall has won several awards for his portrayal of Dexter, including a Golden Globe.