John Lithgow joining 'Dexter'

Actor to play a serial killer

Emmy and Tony winner John Lithgow is joining the cast of Showtime's drama "Dexter."

Lithgow will appear in all 12 episodes of the show's upcoming fourth season, playing Walter Simmons, Miami's latest serial killer and Dexter Morgan's (Michael C. Hall) new nemesis.

Simmons is described as an unassuming, mild-mannered suburbanite who has been living a dual life as one of America's most prolific serial killers, dubbed the "Trinity Killer" because of his proclivity to kill in threes.

After being tracked by FBI special agent Frank Lundy (Keith Carradine), Simmons relocates to Miami, where Dexter is brought on to assist in the investigation and becomes fascinated with the killer's skills.

Season 4 of "Dexter" premieres Sept. 27.