Castle: 3x6
3XK
When a beautiful woman is found dead in an alley, all clues point to her being a victim of the notorious Triple Killer. The Triple Killer, or 3XK, terrorized New York City four years ago, then mysteriously disappeared. Now he’s back. In a deadly battle of wits, Castle and Beckett race against time to stop 3XK before he claims his next victims.
3 - 1A Deadly Affair Sep. 20, 2010
3 - 2He's Dead, She's Dead Sep. 27, 2010
3 - 3Under the Gun Oct. 04, 2010
3 - 4Punked Oct. 11, 2010
3 - 5Anatomy of a Murder Oct. 18, 2010
3 - 63XK Oct. 25, 2010
3 - 7Almost Famous Nov. 01, 2010
3 - 8Murder Most Fowl Nov. 08, 2010
3 - 9Close Encounters of the Murderous Kind Nov. 15, 2010
3 - 10Last Call Dec. 06, 2010
3 - 11Nikki Heat Jan. 03, 2011
3 - 12Poof! You're Dead Jan. 10, 2011
3 - 13Knockdown Jan. 24, 2011
3 - 14Lucky Stiff Feb. 07, 2011
3 - 15The Final Nail Feb. 14, 2011
3 - 16Setup (1) Feb. 21, 2011
3 - 17Countdown (2) Feb. 28, 2011
3 - 18One Life to Lose Mar. 21, 2011
3 - 19Law & Murder Mar. 28, 2011
3 - 20Slice of Death Apr. 04, 2011
3 - 21The Dead Pool Apr. 11, 2011
3 - 22To Love and Die in L.A. May. 02, 2011
3 - 23Pretty Dead May. 09, 2011
3 - 24Knockout May. 16, 2011