Episode 306: 3XK

CASTLE - "3XK" - When a beautiful woman is found dead in an alley, all clues point to 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. Lee Tergesen of "Oz" (as Marcus Gates, a violent felon who becomes the prime suspect in the investigation) and Michael Mosley of "Scrubs" (as Jerry Tyson, a former prison friend of Gates) guest star in one of the most thrilling episodes of the series to date, on "Castle," MONDAY, OCTOBER 25 (10:01-11:00 p.m., ET), on the ABC Television Network. (ABC/RANDY HOLMES) NATHAN FILLION, STANA KATIC