Castle worked out that Ben Conrad was a scape-goat, shot by the real serial killer. He was too late to prevent Becket's place being bombed, but she survived, having being in the bath at the time. Shaw's profile and databases lead to a likely suspect, Doherty, actually deceased: the new fake identity. The team stakes his place, but the killer expected them. He gets away, but is identified. Becket is barricaded in castle's home, but the killer captures Shaw. Only Castle manages to think like him and prevent a big bang finale.
Did You Know?
In Season 1 (Home is Where the Heart Stops), Castle and Beckett are at the shooting range, and he gets three shots in the 10-ring with ease; however, in this episode of Castle when he is aiming the gun at Dunn, he shoots him in the hand, but then says to Kate "I was aiming for his head." While Castle is shown to be an excellent pistol shot on the range, he is not a trained police officer or a skilled/experienced fighter. Therefore, it's entirely plausible that having to shoot under stress would severely affect his marksmanship. This happens even to trained police officers and soldiers. See more
[Castle rushing into Beckett's apartment which has been blown up and is on fire
Kate! Are you in there? Kate?
Performed by The Genders See more