This is the second part of a two-part episode. Castle and Beckett remain trapped in the frozen storage container while the NYPD and the Department of Homeland Security continue to search for the dirty bomb. Alexis' worried call finally results in help arriving, including Beckett's boyfriend, Josh. Now back on the task force, Beckett and Castle team up with Homeland Security, to follow the trail of domestic terrorists. But can they find the bomb, and defuse it in time?