Janet Montgomery has starred with David Tennant in Spies of Warsaw and as Freda Ward Dudley in the 2013 Christmas Episode of Downton Abbey, and she's having an incredible time with her current role.

As Salem's most power witch, Mary Sibley, she gets to play a wide range of emotions including incredible power and intense loss. 

We had the chance to chat by telephone with Ms. Montgomery this past week and she shared how she became involved with Salem, why Mary made the choices she did as well as her thoughts on Mary's future among other things. Excerpts from our conversation are below...

TV Fanatic: What drew you to Salem?

Janet Montgomery: Well I first got involved in the project when I was in London just over a year ago and was sent the script and was told that Brannon Braga was in London shooting Cosmos and he wanted to meet with me. So I read the script and really liked it. I was sort of frightened by the character, because she exudes so much power and I hadn't really read a part like that for someone of my age. So I was really excited by that. I sat down with Brannon and he was pretty excited by the thought of me playing it. He had seen Spies of Warsaw and Dancing on the Edge, yet he hadn't seen me ever play an American before actually sitting down with me, which was funny. So that was a conversation we had about Mary, whether she would be English or American.

TVF: It works, the way you're playing her. It doesn't really matter, in that time period.

JM: Yeah, it's hard to know what the accents were in that time period, but I don't think it matters that I'm the only British person in Salem.

TVF: As you mentioned, Mary is certainly very powerful right now, but she certainly didn't start out that way. Do you think she's an unwilling pawn who got caught up in something she didn't understand or do you think she's all in?

JM: I think that it's hard to really pinpoint. You have to take responsibility for your actions and your choices, but that being said when you're given so little choice you can't really help but sympathize with Mary. Yes, she was having sex out of wedlock and you can say that was her choice, yeah, but the choice after that, there was very little choice. For most of us your survival instinct goes in and you just do what you have to do to survive. I think that's what happened with Mary, really.

TVF: Do you think once John Alden came back, she regretted her decision?

JM: I think she's probably regretted her decision on and off. You know, like most things that you do, you question whether you made the right decision. I think even before John came back, in Salem Season 1 Episode 2, she talks about not being able to forget her baby -- she thinks about it every day. So I think it was before John that she regretted her decision, but definitely the return of John awakens a lot of feelings and what could have been if she hadn't done what she did.

TVF: How difficult is it for you as an actress to play both sides of Mary? The really powerful woman and the sympathetic side, sometimes with the flip of a switch? You're making it very difficult to dislike her.

JM: You know, it's challenging. Like anything, when you're trying to have your emotions at the turn of a hat -- because that's the kind of person Mary is, her emotions are all at the surface. It puts her at an advantage in life, but also a disadvantage. For me, it just requires a lot of concentration and a lot of work before hand so I can tap into these things and not struggle when I'm on set. But honestly, there are days when you're tired and your brain isn't working as quickly and your emotions aren't working as quickly as you want them to, but luckily I'm working with such generous actors and with very supportive bunch, the crew and everybody so if I struggle a little bit, they give me a few extra takes.

TVF: Do you have a particular Mary moment you most enjoyed playing?

JM: I try to control my temper as much as possible and don't get often get to lose my temper, like most people in real life -- you don't often get to lose your temper. But getting to play Mary I do get to really lose my temper and there's a scene in Episode 9 where I have this massive fit of anger and end up smashing quite a lot of things and it was really quite a lot of fun to do.

TVF: What's the most difficult thing about playing Mary?

JM: It's exhausting. It's hard to switch off. I get myself to a certain state in order to play Mary, and whether that is emotional, angry or sad or impassive and sort of bitchy, whatever the scene requires, it's hard to always switch that off when you're tired and to kind of stay in control of it and not end up being rotten on the inside. That's the hardest part as an actor, because to play things truthfully, you hack into them within yourself and then you feel kind of rotten. So I guess, yeah, being kind to myself while staying in character.

TVF: Awww. That's kind of sad.

JM: You know, it's tough with her because I sympathize with her a lot, as anyone should when they're playing a difficult character like Mary. But there's also, you know, the choices that she makes, I read the scripts and stuff, the things that she says and does, those feelings you can't help but feel yourself in order to play them truthfully. And they kind of sit inside you and kind of make you feel like ewww, icky.

TVF: It would be hard to shake off.

JM: Definitely. It was nice because I had my family here and I had my mum and my step-dad and my boyfriend and my best friend. They came out for about a week and they stayed with me. That was quite nice because they all saw how much I had been working with the character and it is easier to shake off when you're around people who know you very well. Usually I'm just in Shreveport and when I finish work I come home to an empty house, I make myself something to eat and I go to sleep. So it was nice to be around people know me and not Mary.

TVF: Who do you think Mary's biggest ally is in Salem?

JM: Hmmm. That's a good question. I think since the return of John, it's probably John. Tituba and her have a very dubious relationship, and it's hard to pinpoint what's really going on with them. I don't think Mary really trusts Tituba.

TVF: I don't think she should.

JM: No. And I don't think Mary really has anyone else to turn to. I mean Hale is pretty useless and Rose is a pretty tricky character, as you'll see. I don't really want to say anything because you're only through Salem Season 1 Episode 4 and we're through Episode 12 so I know what happens to these characters.

TVF: That's exciting for you. And you get a second season.

JM: Yes! That's so exciting and it's so nice when we finish in a few weeks knowing that when we get a break we can come back to a job. It's such a blessing for us to have that. We all feel really lucky.

TVF: Have you thought about where you would like to see Mary end up?

JM: I have, yes. I personally don't think that Mary should get everything that she wants. I don't think that that's how life works and I don't think she would be happy if she ended up with John at this point. I think there is a certain amount of guilt and punishment that she feels she deserves. I mean, I'd like her to get out of Salem to be honest, but I mean she's made this pact and I don't think that getting out of Salem is really an option.

TVF: And she can't because you're the star and you're heading into a second season. So, there's that!

JM: That's a very good point. Mary's on vacation!

TVF: And Salem goes wild! Since you're filming up through Episode 12 already, are we going to see a bit more about what the witches end game is? We're guessing about what will happen if the Grand Rite is achieved, for example.

JM: Oh, definitely, I'd say that you are and it's going to be given to you in little pieces each week until like 12 and 13 when you fully understand exactly what this Grand Rite is and how they're going to achieve it. And they're so close by then. I don't know what happens in Episode 13 yet because I haven't read it, so I can't tell you whether I succeed in taking over Salem.

TVF: If you were Mary and you took over Salem, what would you do with it? I've been kind of wondering what their next step would be.

JM: Well, I think Mary has an idea of what will happen when the Grand Rite is completed but who knows -- the devil is a tricky customer -- so who knows if that would happen. I think there's always the fear that when they complete this Grand Rite that it might not be everything that Mary has been promised.

TVF: So she could still be a pawn played by the worst of them all -- the devil.

JM: Yeah. But what I do like about the script is that, you know, there was a great line where I said "Not my God," and I was talking about my God and what my God expects from women. And in this time period and the way the churches treated women, it makes sense why women turned to a different God, you know, call him the Devil, call him Satan, why they turned to a different God in order to have a voice.

TVF: I'd say some of that still resonates today. Is there anything else you can share before you go?

JM: You know, I'm just having so much fun. I sat down with the cast and we watched Episode 4 together; we're watching all the episodes together. We're all really excited about what we're making and we're just so lucky that people are really responding to the show. You never know when you're making something whether it's resonating, but I think it's started to find it's stride and to have WGN promote the show so well and for to have already have found an audience is so exciting. We're so happy.

Salem airs Sundays at 10 p.m. EST on WGN. If you need to catch up or don't get WGN, you can watch Salem online via TV Fanatic to see what all the fuss is about!

Carissa Pavlica is the managing editor and a staff writer and critic for TV Fanatic. She's a member of the Critic's Choice Association, enjoys mentoring writers, conversing with cats, and passionately discussing the nuances of television and film with anyone who will listen. Follow her on X and email her here at TV Fanatic.