Ryan, Beckett and others in “Under Fire”

Ryan

This is Lieutenant Delia Burton. She's a fire investigator with FDNY. Detective Beckett, Mr. Castle.

Beckett

Nice to meet you. So this was arson?

Well, it's looking that way. I found miniscule traces of accelerant at the flashpoint.

Castle

So the killer set the fire to cover up the murder?

Except there's no accelerant on the body, and the fire's flashpoint is deep in the building. You know, normally when you're disposing of a body, you're gonna make sure it burns.

Beckett

So maybe our victim surprised the arsonist.

Castle

And the arsonist killed him, silencing him as a witness?

Lt. Delia Burton: That's how it looks to me. Then again, homicide's not my specialty.

Beckett

No. Uh, but fire is. Would you mind keeping me in the loop in case you find anything else?

Sure. As soon as I know what happened, so will you.

Castle

Whoa. What was that?

The building. You guys should probably go.

Castle

[turning and hurrying away] Sounds good. See ya!

Beckett

[embarrassed] I'm marrying him.