She might have been killed by a psychotic plumber lying in wait.

Castle: Ryan, you played the C card?
Ryan: You weren't around. Somebody had to step up.

Beckett: He is resourceful but he's not that resourceful.
Ryan: He got you to marry him, didn't he?

You know what would really suck, if Castle solved this case before we did.

Someone has to provide us with out of the box thinking now that Castle's not around.

Ryan: You know what time it is? It's Ryan time.
Esposito: Please just stop.
Ryan: My name's Ryan and I hate lyin'.

Ryan: That strains credibility.
Esposito: Yeah, in a good way.

Castle: I was raised by a single mother. Hard Kill was how I got my bro time.
Ryan: That explains so much.

Well, you know the thing of it is, you know what it's like to not have a father, you'd make sure your kid never felt that way.

Esposito: Kind of like we let you get away with not inviting us to the wedding.
Capt. Gates: Well at least you were invited to the Champagne toast.

Esposito: Really, we didn't get that call.
Ryan: Once again, not invited.

What we could use right now is a crazy Castle theory.

Castle Quotes

Sometimes the hardest things in life are the things most worth doing.

Castle

Castle: How do you know when you're in love?
Beckett: All the songs make sense.