Who knew Mary Elizabeth Winstead had so many surprises up her sleeve?

Since her big debut over decade ago with a rocket ride into stardom in a quick succession of high-profile films like "Final Destination 3," "Bobby," "Black Christimas" and "Grindhouse: Death Proof," Winstead has steadily built an impressive acting resume. Her recent roles have led to a second explosion of exposure in a number of head-turning projects.

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Along with a starring role in PBS' Civil War drama "Mercy Street" and the surprise Sundance Film Festival darling "Swiss Army Man," Winstead's biggest coup was the one she had to keep to herself long after the cameras stopped rolling. "10 Cloverfield Lane" may top even "Star Wars: The Force Awakens" as the most mysterious of producer J.J. Abrams' now famous "Mystery Box"-style endeavors, with a jaw-dropping trailer and release date that came seemingly out of nowhere, a possible link to the Abrams-produced found footage monster movie "Cloverfield" and little more for audiences to chew on ahead of its release this Friday.

Still keeping her secrets pretty close to the vest, Winstead was able to tell Spinoff Online what she could about the project -- just enough to keep the Bad Robot enforcers at bay.

Spinoff Online: The whole "10 Cloverfield Lane" movie just sort of got sprung on the public -- like, "Surprise!" How did you keep that secret? Did you have to, or did you just like, 'Oh, no one's talking about this movie'?

Mary Elizabeth Winstead: A bit of both. I knew everything about the movie I had to keep secret, but the way that I kept the release secret and the trailer secret is that I just knew nothing about it. Nobody told me anything. So I was very excited when the trailer came out to know that the movie's coming out soon. We always had the release date, but there was not a lot of promotion. As an actor, you get a little worried, like "Oh no. Are they really going to release it?" And I guess the whole time they were just planning this kind of super slick thing to just drop it on everybody.

The scenes we've seen with you and John Goodman are so intense -- was it an intense sort of filming experience?

It's incredibly intense and kind of gets more and more intense as it goes on. But it's also fun. There's a lot of funny moments to break the tension, and it was such a great group of actors. It's basically just me and John Goodman and John Gallagher Jr., who couldn't be lovelier -- maybe the two loveliest, nicest people ever to work with. And so is Dan Trachtenberg, the director, as well as J.J. It was just like, I mean, we were talking about how we're not going to have a lot of stories for like the press. It was just so pleasant. It was so lovely.

We think maybe it's set in the "Cloverfield" universe--

Well, that's the thing that I couldn't really talk about. As J.J. calls is, it's a blood relative, and I think that that's the best kind of wordage to use right now. Then, once people start seeing it, we'll know more.

"Cloverfield" had a unique hook in the way it told its story. Is there something like that?

Yeah. I think, anything that's done by Bad Robot, you know that you're in for a bit of a ride, and you know that it's not quite what it seems on the surface. I think that's a calculated thing on their part to not give everything away, which I think is really smart and I think evokes another era of movie going that we don't really get too much anymore. I think it's really exciting to not know everything when you go in to see a movie.

Shifting gears a bit, let's talk about your Sundance sensation.

I'm in this crazy film called "Swiss Army Man," with Daniel Radcliffe and Paul Dano. It is probably the most insane thing I've ever done. I don't really get to be that crazy. I'm really just reacting to the insanity of... when I describe the film, it's almost like I can't quite wrap my mouth around the words. I just feel like, it's one of those things you just have to see it to know because it's just too insane, but it's also so sweet and endearing and uplifting and unlike anything else.

You also worked on John Krasinski's next directorial effort, "The Hollars." Tell me about that experience.

It was so much fun. I really just flew out for a day to Mississippi where they were shooting just to play his ex girlfriend in a brief appearance. So I can't say that I was a big part of the film, but I think John is super talented and such a sweetheart and so funny. And he got such an incredible cast together for this film. I didn't get to see it. I think it's premiering this week at Sundance, and I was there this past week. So I'm hoping to see it in LA when they screen it next.

Were you friends with him beforehand?

I had never met him before. But we had mutual friends. So the script kind of got to me through friends saying, 'Hey, he really wants you to come do this part, is a big fan of yours.' I'd only heard the loveliest things about him. So I thought, this will be a fun thing to go do for a day. And oh my God, I'm such a fan of his wife [Emily Blunt]. I was a little bit star struck when I met her on set.

You're quite busy these days. "Mercy Street" was picked up for a second season. What else is going on for you?

I'm getting ready to start shooting a show for CBS called "BrainDead," which is from the creators of "The Good Wife." So yeah, it's a busy time.

"10 Cloverfield Lane" opens the mystery box in theaters nationwide March 11.