The stage was set on Castle this week. Adrian Pasdar debuted as a Homeland Security Agent in the face of a major threat facing the city, clashing with Castle and Beckett, but also agreeing on one thing:

There's a serious possibility of catastrophe ahead, made even more grave by the way the installment concluded: with Castle and Beckett locked in a room.

On the second half of this special two-parter, "Countdown," the race will be on. Can a crisis be averted? Watch the official ABC promo now and get an early idea:

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.