Castle and Beckett visit a crime scene in this clip from "Demons." It focuses on the death of a known... ghost wrangler.
Castle tries to give Alexis some advice in this clip from "Demons." The speech doesn't go so well.
Castle and Beckett enter the world of the supernatural this week. That makes Castle very happy, as you can see here.

Castle Season 4 Episode 6 Quotes

If you say ghost, I'm sending you home.


Alexis: Dad, are you using me as a shield against flesh eating zombies?
Castle: No, I'm just trying to give you a better view.