EpisodesDaily.com Airing February 20, 2012 Episode Summary: In the explosive conclusion of a two-part story arc that began last week with "Pandora," Castle Beckett race to find the "Linchpin" in order to stop the first domino in a chain of events which will plunge the United States into war. ABC,Alexis Castle,Castle,Castle 4x16,Castle 4x16 Promo,Castle Season 4,Castle Season 4 Promo,Castle Season 4x16 Preview,CBS,Entertainment,episode,FOX,full,Iron Gates,Javier Esposito,Jon Huertas,Kate Beckett,Kevin Ryan,Lanie Parish,latest,Molly C. Quinn,Nathan Fillion,NBC,new,online,onlineseason,onlinetv,part1,Penny Johnson Jerald,play,preview,promo,Richard Castle,Seamus Dever,Season,Season1,Season2,Season3,shows,Stana Katic,Susan Sullivan,Tamala Jones,thecw,trailer,tvtvseries,Victoria Gates,watch,watchtv
