When “Marvel’s Jessica Jones” returns for its long-awaited second season on March 8, the sarcastic, super-powered sleuth (Krysten Ritter) is just as tortured as ever. She may have vanquished Kilgrave, but she’s on the trail of whatever caused her to get her powers in the first place — a trail that leads her to the mysterious, as-yet-unnamed character played by Janet McTeer.

The Tony-winning actress may be best known for her theater roles, but McTeer is now plunging headfirst into streaming — not only is she starring in “Jessica Jones,” but she’s also now in production on season two of “Ozark.”

Her character on “Jessica Jones,” who is central to this season’s mystery, doesn’t make her debut until the third episode, but McTeer promises it gets “really interesting” once it kicks off. For now, she jokes, “It’s like doing a jigsaw puzzle without any of the pieces.”

Ahead of the show’s premiere, McTeer talked to Variety about why she signed on for a superhero show, whether her character is this season’s “big bad” — and why she likes keeping secrets.

What made you want to sign on for “Jessica Jones”?

When I spoke to [executive producers] Melissa [Rosenberg] and Raelle [Tucker], they were just so interesting and so clever and so passionate about the project. They sent some scripts which I really liked, and so I watched the first season. I thought the first season was really good, but the second season is even better. When people are writing for something that’s already a success, it means they can be bigger and broader and bolder. I thought it was a great, fun opportunity to play a part that I hadn’t played before on a venue that I hadn’t played before.

What did they tell you about your character in advance? How much did they let you know?

They told me everything about my character — where she was going, what the storyline was for her, what that meant. They were still writing some of the episodes, but I kind of knew where everything was going and what was going to happen. I knew all about it before I started off.

How would you describe your character?

I would describe her as very driven, very intense, very goal-oriented and very, very, very complicated.

Will we learn her name?

Eventually. (Laughs.)

Are you a fan of comic books, of the superhero genre of TV? 

To be honest, I haven’t been that much, because I’m ridiculous and I never have any time. When I do, I’ve usually got my nose in a book, but then I did start watching some and I must admit I really had a lot of fun. I’ve begun to watch a lot more Marvel stuff, and I’ve been having a really good time.

But this is also so different from the rest of the genre, given that it’s so female-led, from the showrunner to the star to the supporting cast.

That was a good eighty percent of the fun of it. All of the women across the board involved in this project are really great women. That’s a great thing to be a part of. It’s a privilege to be a part of that. Across the ages, as well. It was really nice.

Has it been hard for you to maintain all of the secrecy around your character?

No! It’s been bliss. Everyone just leaves me alone. My favorite! There’s a reason why I live in the woods of Maine; I like to do my work and I like to go home.

So where does the line between your character stop and you start?

There isn’t one. I am everything that the character is. (Laughs.)

Is she good? Is she evil? Somewhere in between?

I am that character so I would say she’s not evil in the slightest. But I suspect other people might have a different opinion.

Just how dangerous is she?

Depends on your perspective.

Is she a friend to Jessica or a foe to her?

Maybe a little bit of both…

Would you characterize her as the “big bad” of the season?

(Long pause.) Probably not. Certainly the most difficult.

How did you find your way into playing this character? 

It took quite a lot of imagination. Quite a lot of hammering out a story for myself with the help of Melissa and Raelle. Lots of kind of getting the story clear in my head of what happens when and why and what the effect those things have on me — and keeping that within the bounds of reality for myself.

Did you enjoy filming her stunt scenes?

It was great! I loved it. I’ve never had to do anything like that before. I really, really enjoyed that. Great, great fun — but hard on the knees.

What makes you say yes to any given part? What do you look for?

I think I have different criteria. Sometimes there are what my husband calls no-brainers — when it’s a great part or it’s with great people or it’s a great production. Those are the ones you just sort of smile and go, yes, absolutely I want to do that, I want to make that work. And then there are other ones that you do where you don’t have all the information or you have to really figure out where you’ll fit it in with your family life, and somewhere along the line you have to pay your mortgage, how much time away from home is it and all of those things that you juggle constantly certainly at this stage of one’s life. It was easier when one was younger. And I suspect it will be easier when I get older.

Do you feel like TV offers you more opportunities right now?

I think at the moment it does, without a shadow of a doubt. There just seems to be so much wonderful stuff being made and original series being made. It gives a platform for a lot of really great original stuff that’s harder to get funding for. That seems to be happening across the board in a way that is fantastic for my profession. I’m playing a part which I don’t feel I’ve ever seen a woman play, which is really nice.

How do you think fans will respond to this season?

I hope that they’ll love it. I hope that they’ll be interested in it. It’s surprising and interesting and it will hold their attention.

“Jessica Jones” returns for its second season on March 8 on Netflix.

Watch the trailer for season 2 below: