Tonight's season finale episode of Castle will bring us smack dab in the middle of Johanna Beckett's murder, a case that's gone unsolved for over a decade. The people involved in the cover-up still want Kate dead, but Rick managed to strike a deal with Mr. Smith — the man Captain Montgomery sent his files to in the Season 3 finale — to keep the detective safe.

But all that changes tonight when a thief breaks into Monty's widow's house, steals his old computer, and winds up dead. Beckett hurls herself back into the case, putting her life in the crosshairs once again. And according to Seamus Dever, with whom Wetpaint Entertainment spoke exclusively, there's so much more at stake than Castle and Beckett's relationship.

As the layers surrounding Johanna Beckett's murder begin to unfurl, we'll get a taste of just how big this thing is.

What can we say about Caskett?

What should we say about Castle and Beckett? I think everyone saw the teaser. It's one of the things that ABC teased where Castle says something like “I love you.” We can already tell that there's something that's hinted there. I think people who have — let me put this delicately — I think people who have wanted for a long time for there to be some progress on the relationship of those two will finally be happy.

Hurray. Well, the teaser has her dripping wet, like lunging herself towards Castle. She probably doesn’t trip.

Yeah. Maybe she was like lunging because someone tied her shoes together, and she's just falling. And then he just happens to be there. And she's like, “Oh, no, my shoes are tied together!” You never can tell until you actually see the episode.

The episode itself, is it almost entirely focused on Beckett's mother's murder?

Yeah. It actually starts out very interesting. There's a crime that we're investigating, and we get an address location because there was a break‑in at a house, and we get the address of where the break‑in was. And it turns out to be Montgomery's house. So Montgomery’s widow is involved, and we get to go back and see her again.

And from there it grows, and the onion layers get peeled back more and more. But yeah, it's exclusively investigating that. And we have the new Captain who wasn't around for all the old stuff. So it's sort of like there's some tension involving that as well because I feel like there's two different worlds colliding. Like the new way and the old way that are coming toget

We have been wondering if there's more to Captain Gates than we think. But from what you're saying, she's the new world?

The way she's been set up from the very beginning is, she represents a tough‑minded, “Let's get murders off the books” type. "It's great that you have this vendetta, Beckett, but we have to think realistically about manpower.” She's more practical rather than emotional.

We learn that the reason why Montgomery was so emotionally invested in Beckett's mother's murder is because he was part of that group. So, I think, her being removed from it, she's just about numbers. She's like, “If there's no other evidence, then we shouldn't do something about it.” And what ends up coming up is that we start investigating something and we're trying to keep it away from Gates.

So again, with those lines being drawn, you'll start to see it very clearly laid out where Castle feels about doing the right thing, means something very different than what Beckett feels about doing the right thing, and the same with Esposito and Ryan. So I think all of us, the four of us, get to really choose what doing the right thing means, and I think we all have different definition. And we sort of all come up with a different answer at the end of the episode.

Well, as far as the murder itself, will there be closure as far as the mystery goes?

I can't say. Again, my theory on this is it's going to get so big, that it's going to be like, whoever the president was at the time of Beckett's mother’s murder. It’s going to be like Bill Clinton, Beckett’s mother’s murderer. It's just going to get bigger and bigger and bigger.

But let's just say, some things do involve Mr. Smith coming back. There's some interesting things involved with him, and I think you see some developments on that end. So there's a lot of stuff that happens in this episode. That's why it took ten days. He comes back and that's sort of involved a little bit further. We find out a little bit more about his story.

The secret that Castle's been carrying with him all season, I take it Beckett will find out about this deal?

Well, we'll see. There's something that happens to it, and I think it's something cathartic that happens with both of them because they both have secrets.

You saw this last episode that just aired on Monday. She admitted that she had been going to therapy and was trying to work through some things. And she's also been keeping the secret. We find out that she remembered everything that happened to her when she got shot. She remembers him saying I love you. So they both have secrets.  

So, yeah, this is Castle's secret that he's been holding on to. So we'll see what progress is made with that.

We never found out who Dragon was. Will we know who Dragon was?

I don't know. It still seems like it's a group that's happening, but I don't know if we learn a little bit more about who's involved. There's something else that happens that goes there, and Beckett gets to confront some things because of it. I can't give you any more specifics. I'll ruin things if I tell you too much.


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