First, I think Castle has only been married two times not three (Melissa Malono's character was the "one that got away." He didn't actually marry her but she might be why you're thinking there are three former Mrs. Castle.).

Second, I'm not of the mind that a happy couple will ruin a show. One example, "Heart to Heart" (or did they spell it "Hart to Hart?"). They were married on the show from day one and that show ran forever. It can be done and still remain fresh and funny and dramatic. It's called good writing, acting, and direction. Sometimes I think it's an insult to all the creative people involved when people say you can't put a couple together until the end of a show's run. The whole "star crossed lovers" thing can get old too. Real life couples have ups and downs in their relationships and still remain "together" for the long haul. Why can't these two? Mix in great banter/comedy with intriguing murder mysteries/drama and it's still a great show - even with Castle and Beckett happy. And how refreshing would it be for this show to succeed at it?!

While I'm sure the producers, writers, cast and crew have always known they have a quality show I think the sudden success of the show has come as a bit of a surprise to them. Like Nathan said, he's never had a second season of anything. He's not quite sure what to do or what comes next. Hopefully, the show runner had, or now has, a "five year plan" for the show so that things don't move too slowly or too quickly or causes them to paint themselves into a corner. That's what cause's a show to "jump the shark," - the "now what?" situation that usually happens around season four or five when things weren't planned out well ahead of time.

So what was the song they played during the perp walk?

Love Castle. One of the producers was mentored by Steven J. Cannell, and that's why this show works so well. Great to see Det. Tom Demming added to the mix. Castle needs the competiition and the tension to keep it going. Remember what happened with "Moonlighting?" Besides Castle's already been married 3 times. The strong willed Kate scares him, and that's part of the fun of the show because both of them are so attracted and so relunctant to do anything about it.

Loved the Casablanca references from Castle's mother first and then from Castle. Part of the fun with this show is finding all of the in jokes.

I kinda spaced on the whole Castle/Becket plot--so long as they don't jump the shark, I kinda don't care what they do.

What was interesting was the A story. While I called the IA cop as the bad guy, it was still a fun ride. It was also neat to see some back-story on a minor character, Esposito in this case.

Particularly sweet: "...and this is my other partner, Castle." Interesting to see the relationships in play.

Still digging the relationship between Castle and Alexis. On one hand, I thought it was cheesy with their poker suits. On the other hand, it fits--Castle is a big kid who likes to have toys (I also remember "onion goggles"). And, Alexis is growing up right.

I love that Trucco is a worthy of Beckett and therefore a real challenge for Castle. Its about time he figured out why he hasn't made a serious move on her and not just his usually flirting and innuendo. The last few episodes should be fun.

I loved this ep (and most of the ones before it too)!
And I'm so torn - obviously I want to root for Castle, but Demming... well, he's pretty hot too. And Demming lost the girl when he was on BSG so he does deserve a break...

My daughter & I are glued to the tv set every Monday night for Castle. We both thought this episode was one the their best - very well written, and although I kinda guessed Ike was "undercover" to catch the big bad guy, I was really thrown when they went after Demming! Nice twist! Every cast member is awesome and shines!

One of the best episodes yet. Great mystery plot that was very well acted by all. Plus, an excellent twist on the evolving romance between Castle and Beckett. Nice way to continue to tease the audience by adding a "competitor". Did you see the twinkle in Beckett's eyes each time she knew that she made Castle jealous? She (Stana Katic) deserves lots of recognition for her versatility playing both the drama and the comedy.

The gym scene appeared to be inspired by "Heat Wave". Art imitates meta-art.