This is by far the best and funniest episode of the season so far...at least for me. This had a little bit of everything in it. Mystery. Caskett. Adam Baldwin, Molly stuff, Espo and Ryan!!! Just brilliant. I liked the start of the episode where they were basically mirroring Castle and Beckett with Slaughter and Laura. It seems most relationships are either a commentary on the main one or some kind of mirror of it. I was laughing through most of the episode...and distracted by Baldwin's excellent performance as Slaughter (basically I found him to be the Castle'Verse version of Jack Bauer!) to notice the real killer. Michael Dorn returns in a poignant scene with Kate. Molly was looking stunning in this episode, as was Stana. I also loved the score and how this episode was shot.
Oh and for I think the first time in a long time we finally get a "Frozen Heat" update, and as I thought Rick seems to be going through writer's block stemming from being distracted from all the stuff going on with Kate this year.
Finally, I hope Baldwin comes back next year, I'd love to see Slaughter return.