A scene from “Flowers For Your Grave”

Kate Beckett: Why are you here? You don't care about the victims, so you aren't here for justice. You don't care that the guy's aping your books, so you aren't here 'cause you're outraged. So what is it, Rick? Are you here to annoy me?

Rick Castle: I'm here for the story.

Kate Beckett: The story?

Rick Castle: Why those people? Why those murders?

Kate Beckett: Sometimes there is no story. Sometimes the guy is just a psychopath.

Rick Castle: There's always a story, always a chain of events that makes everything make sense. Take you, for example. Under normal circumstances, you should not be here. Most smart, good-looking women become lawyers, not cops. And yet, here you are. Why?

Kate Beckett: I don't know, Rick. You're the novelist. You tell me.

Rick Castle: Well, you're not bridge and tunnel. No trace of the boroughs when you talk, so that means Manhattan, that means money. You went to college, probably a pretty good one. You had options. Yeah, you had lots of options, better options, more socially acceptable options, and you still chose this. That tells me something happened. Not to you. No, you're wounded, but you're not that wounded. No, it was somebody you cared about. It was someone you loved. And you probably could have lived with that, but the person responsible was never caught. [realizing he overstepped] And that, Detective Beckett, is why you're here.

Kate Beckett: Cute trick. Don't think you know me.

Rick Castle: The point is, there's always a story. You just have to find it.