'The Blacklist' Star Megan Boone on 'The Kingmaker,' a Darker Path for Liz, and Working With James Spader

"The Blacklist" (Mondays at 10 p.m. on NBC) is one of the best, most intense freshman dramas of the season, and the stakes have never been higher. After things finally came to blows between Agent Elizabeth Keen (Megan Boone) and her husband Tom (Ryan Eggold) — who, she discovered, only met and married her as part of an undercover assignment — the second most mysterious man in her life had a few parting words that made Liz and all the viewers question everything.

"I am not here to hurt you, Liz. My job was never to hurt you. I'm one of the good guys," Tom said. "Reddington… he's not what you think."

[Related: 'The Blacklist' Cast Talks 'Batman' Inspiration and Promises Answers... Eventually]

Yep, that random key Liz found her husband hiding went to a safety deposit box (when do they not on TV?), and in the final scene of the episode, she opened the box and opened an envelope, ostensibly discovering who Red (James Spader), the No. 1 most mysterious man in her life, really is.

Yahoo TV caught up with Boone to talk about what's next and who she can trust now, and she teased that Liz is about to go "off the rails" and "to a darker place." She also commented on her mercurial co-star (and on-set ally) James Spader.

But first, watch our exclusive sneak peek of "The Kingmaker" (Monday, April 28):

OK, that Liz and Tom fight scene this week was epic. How long did you have to prep for that?
Yeah, we had fun with it! It was actually a unique fight because it was not just a fight between two people — we wanted to destroy the brownstone completely, the brownstone that we lived in together, sort of symbolically destroy our home at the same time. So the choreography had to be a lot more intricate than normal fight scenes because we were using the furniture, the walls, all as props. We actually did a whole rehearsal the Friday before the week we were going to go shoot it to choreograph it and map it out, and then the day we shot it we just did it in sections.

The last thing we saw was Liz opening the envelope, presumably finding evidence that Red is also not who he says he is. What can you tease about what's in that envelope?

It's gonna ruin a relationship that's very important to her. It's yet another one of those.

She just lost Tom for real, we think, and Red is her last ally… how is she emotionally when she finds out?
In my mind, she's just completely despondent, detached, and jaded at this point. She's going to go to a darker place.

Is that kind of fun for you?
It has been… actually I've been really itching for it. I've known all along, from the beginning, that this was where we were headed with her because it was the only thing that made sense for the story. I just knew that it was going to go there, and I was a little bit impatient about it, you know? I was ready for her to stop being somewhat naïve and so thrown by everything and so open-hearted, because the people around her weren't deserving of that at all. Now she recognizes it, and because it's the situation she's in and what life has handed her, she's just going to go a little bit off the rails and a little bit darker.

[Related: 'The Blacklist' Renewed For Season 2]

So you have known all season! James was saying at your Television Academy panel that he knows the eventual endgame of the whole series. Do you know as well, or do you prefer to go season-by-season, arc-by-arc, and not play too much ahead?
I know as much as James knows. We've all been in discussion about where it's going to go and our paths together. Liz does not know what Red knows, obviously. In the beginning I wanted to not know — I wanted to block out anything that Liz didn't know — but then as the story progressed and as I got into working on the show, it became essential that I had a sense of where she was going, so I started to talk to the writers more about the over-arching storyline. I'm very involved with discussions with the writers, every episode… there's a really open dialogue behind the scenes here at "The Blacklist." We're all in the same boat, headed in the same direction.

That doesn't always happen… a lot of times in series television, especially for broadcast, you're churning along so fast to keep up and keep the train moving, but this feels more collaborative than most.
Does it really? Because this is my first time on a show. [Laughs.] I hope I don't get spoiled and then end up in a working relationship where everyone's trying to keep secrets from one another… that doesn't even make sense to me!

I think one of the best things about the show is how much you all use your guest stars — they really get a lot to do.
The coolest part of my job, I think, is the guest stars. Each guest star coming through… working with Dianne Wiest, Alan Alda coming in, we had Jason Butler Harner... It's like that every week of my life, which has been incredibly, profoundly satisfying.

But the case this week, "The Kingmaker" (played by Linus Roache), seems to be one that Red isn't so sure about. What can you tease about this episode?

The Kingmaker is the most mysterious blacklister so far. Red knows less about him than he's known about any of them. I think as we move toward the finale, the blacklisters become more nefarious and more mysterious, and Red knows less and less about them. It becomes more of a risk for Red as the season progresses.

Risk for Red means Red lashing out a bit and getting violent, which is always fun to watch.
Exactly. And risk for the whole team, too. I think that we're all on Red's side now, even more than we're on the FBI's side at this point. At least I know that, in a way, Elizabeth is. And what's in the envelope ultimately complicates things for her.

When will Liz turn Tom into the FBI? That's still technically her job, and he's still technically a criminal… isn't he?
You know, the Tom-Liz story is still taking shape, actually. As far as where they're going to go at this point, there's a big shocker in the season finale. It's still up in the air, in the larger sense, especially when it comes to how she's going to handle him legally. I don't think she knows where she stands, on what side of the law. She's starting to go off-course a little bit. She's starting to make choices based on her own desires and her own initiative, rather than what's true to code and what she should be doing in order to be a good FBI agent. We've seen her take that path, and she's going to continue to go darker.

There was a fascinating piece on James in Rolling Stone this week, talking about his OCD and his peculiar tendencies on set, but the most interesting tidbit was from Maggie Gyllenhaal, his co-star in "The Secretary," who said he called her "his ally" on set, that he has to have an ally on every project he does. Who's his ally on the Blacklist?

Who do you think is his ally?

I'm genuinely asking!
Well… James is… he's a great actor, and everything he does on set is about fueling the story. So I think having me as his ally is not just beneficial to his process, but it's beneficial to the story because it feeds our onscreen relationship as well. James is one of the best people I've ever worked with, as far as collaboration goes. He cares so much about me and the show — I really feel that. In this business, it's very hard to find people with such kindness and consideration. Our relationship is very strong — we have a wonderful relationship.

"The Blacklist" airs Mondays at 10 p.m. on NBC.