On the End Scene of Castle 609: Disciple

The majority said that Kate is scared because she finds out that 3XK is alive and is out there to get them. But that look is not of fear but pure, sheer, and utter terror. I've never seen that look before on Kate. My take is that the song means something to her: it was her parents' theme song or it was played at her mum's funeral or it's her mum's favourite song. And the way that Castle looked at her tells that he knows it too. Remember, Castle is the only person Kate opened up to and we don't know what happened behind the scenes.

The lyrics also have something that says that it's not that 3XK will be back because we know he is. The message of the song is tell my loved ones that I'm happy wherever I am and that we will meet again.

All of the 3XK files are missing from the files room and 26 other unsolved cases. What if of the 26, one included Johanna Beckett's file? Beckett, Castle, Espo, and Ryan solved Beckett's mum's murder (Senator Bracken) but they never filed for it to protect Bracken (in a way), and not to make the deal - to keep Kate and those she cared about safe - void, Beckett. And Beckett is the only one not totally targeted by Tyson. He'd targeted Ryan (Kick the Ballistics), Castle (Probable Cause), and now Esplanie.