Castle promised that he’d leave, but he never said he wouldn’t come back. He wonders why the bomb sensor was placed in such an odd location. The plan was to get Diego the baseball card guy to stand there so he’d look up info on the nearby computer. Fosse had a son who had been hidden from him. He was desperate to find the kid. Diego could help. Castle believes his son’s name is the code to deactivate the bomb. They have two minutes to find his name. One minute. Time is almost up. The boy’s name is William. The code needs to be five letters. Billy. Castle punches in the name. Time’s up. Castle was right. Beckett is safe.
Cheers erupt back at the precinct as Castle informs everyone that his partner is off the bomb. Beckett thanks him for staying with her. Castle’s response: Always. Ryan and Esposito rush up to the scene to give hugs to their colleagues, their friends. Captain Gates is there, too. She thinks Beckett should give him a kiss. She knows all about the two of them. The woman’s not an idiot. She says Castle deserves a smooch after what he did. Beckett agrees. She wonders about all their past kisses. Which one was the best? Castle’s asks her thoughts on that perplexing question. Beckett answers, “I think we’re just getting started.” And then they kiss again.