Castle Sneak Peeks: 4.12 "Dial M For Mayor" Photos 1 of 1

CASTLE - "Dial M for Murder" - Derek Webster ("Desperate Housewives," "Damages") guest stars as Mayor Robert Weldon, Castle's longtime friend and the Mayor of New York City. It was Mayor Weldon's political clout that allowed Castle to partner up with Beckett. But now, when a woman is found dead in a car that traces back to the Mayor's motor pool, that partnership comes under fire as the scandal surrounding the investigation threatens to bring down Weldon's administration, on "Castle," MONDAY, JANUARY 16 (10:01-11:00 p.m., ET), on the ABC Television Network. (ABC/RANDY HOLMES) STANA KATIC, NATHAN FILLION