Marshall's next project, The Descent, which was never released in theaters in the U.S., concerned a group of six women adventurers who set out to explore a system of underground caves that they discover are inhabited by strange, vicious creatures. The film was well received and helped solidify Marshall's reputation as an up-and-coming writer/director of thoughtful horror, a step up from the mindless gore and violence of many recent offerings.

Now, Marshall has widened his scope into the realms of action, thrills and science fiction with Doomsday. The film, which he wrote and directed, presents a world in which a deadly virus has been contained in the north of Great Britain by a massive wall, effectively quarantining that part of the country and cutting it off from the rest of the world. Three decades later, when the virus returns, the only hope of finding a cure lies with the survivors behind the wall. Rhona Mitra stars as Eden Sinclair, the leader of the special operations unit sent into the savage hot zone in search of the cure.

Marshall spoke with SCI FI Weekly in a phone interview about his inspiration for the film and the new challenges it presented for him. Doomsday opens March 14.Where did the idea for this movie come from?

Marshall: It came from two different concepts that I had floating around in my head. One was, I was born and grew up in Newcastle upon Tyne in the northeast of England and I lived for a few years in Carlyle on the west coast. And between the two places stretches the remains of Hadrian's wall. It's like the Great Wall of China, but built by the Romans 2,000 years ago, basically to cut off Scotland from the rest of their empire. And I thought, "What kind of circumstances would exist that would mean that wall would be rebuilt in the future?" So I came up with this idea of a virus and quarantining the whole of Scotland, kind of like Chernobyl, and just leaving it to die, because there's no other way of stopping or preventing this virus from spreading. So you have to physically stop it by building a wall and securing the country, basically, locking it down, shutting down the airports, seaports, mining and patrolling the sea around the country, making a no-fly zone, so nobody can go anywhere. And basically just locking everybody in and leaving them to die.

So there was that idea, and then I had this image in my head of these futuristic soldiers facing a medieval knight on horseback, a knight in armor. And it looked like something out of a sort of Terry Gilliam movie. And I was trying to figure out how I could make a story about that image or make that happen without having time travel. And so the two things kind of combined to suggest, well, if I created this quarantined country, what would happen to that country in, say, 30 or 40 years, if people were to go back in there and see if there was any survivors and how would those survivors be living. And I had this idea that maybe they'd be living in the castles, because Scotland is full of these castles. They've been around for hundreds of years; they're going to be around for hundreds of years. They're built to last, and it's an ideal place to go and live. Especially if the survivors have formed themselves into tribes and they're in conflict with each other. A castle would be the ideal place to have as your base. And that was kind of it. There was all these different elements kind of combining.So the survivors are devolving, in a way.

Marshall: Very much so. I thought they would root through history. They're going to scavenge the landscape and all these museums and things and just take what's best for them. So it does become like a regressive society.In your other films, you deal heavily in metaphor. Is there a strong metaphor in this one as well?

Marshall: If there is, I haven't figured out what it is yet. I was too busy just trying to make a rip-roaring action-adventure movie. But if you find any metaphors, I'd love to hear what they are. Unlike Descent, which I absolutely loaded with metaphor, I wasn't really thinking about it on this one. I was wanting to tell a strong, emotional story about the lead character, but also tell just a really great, rip-roaring adventure movie and an action movie.Is part of her journey coming in contact with this regressive society and questioning where she comes from?

Marshall: I would say that's certainly a part of it. I mean, if there is any kind of metaphor in this movie, it's to do with divisions and physical barriers and stuff that we're seeing in the world today anyway, in Palestine and Mexico, whatever, the building of physical walls, and how you interpret it. Is it to keep people out? To keep people in? That kind of thinking. So I guess there's all those kind of issues in the movie. And certainly Rhona's character in the film is a product of this society that's both isolated and divisive and of the future. The trick with this character was to make it different from the six girls in Descent and come up with something new. And she has a very strong kind of emotional journey that she goes on, and around that emotional journey there's this hard shell. She's a tough cookie.You seem to have an affinity for strong female characters. There was a group of strong women in The Descent, and now you have Rhona's character in Doomsday.

Marshall: I don't know. I admire strong women, I love strong women, I married a strong woman. So it's all part and parcel to the kind of films I make. I'm not trying to become like some feminist filmmaker. And it was actually pure chance that this film came up next after Descent. It was not a deliberate choice that I was going to do another film with a strong female role. This idea, actually, I came up with it five years ago. And it was just by chance this was the one that people wanted to make next. So I didn't want to change the character into a guy just to avoid being like The Descent. I wanted to stick with what I'd already come up with. It's not like it's just full of strong women. There's strong men. It's a much more mixed film.What was it that you saw in Rhona that made you want to cast her?

Marshall: She needed to have the emotional undercurrent to carry off the dramatic story. But at the same time, she needed to look like she could convincingly kick you about the head if that was her inclination. And she needed to look brutal and ruthless. And she has that kind of cold look about her when she wants to. And that paid off brilliantly with the character. But at the same time, she connected with the strong, dramatic storyline that drives the whole piece.What about casting the rest of the film?

Marshall: It was long and thorough. It was a much, much bigger cast than anything I've dealt with before. And so many great parts and so many speaking parts. And trying to get the best possible actors in for those roles. We got Rhona in for the lead. We got Bob Hoskins and Malcolm McDowell in for some major roles, which was fantastic. We got Alexander Siddig and Adrian Lester and people like that. And then I managed to get in a whole bunch of guys from Dog Soldiers and a couple of the girls from Descent. What was it like taking on a big action movie for the first time?

Marshall: It's always a challenge, but it was a great challenge. And it was one that I really, really enjoyed doing. The bigger, the better, to be honest. I'd never done anything quite like that before, and I was daunted by it when I first went in. But by the end of filming I just couldn't get enough. The big-scale action stuff was just brilliant. And the more logistically complicated, the better, as far as I was concerned. I loved working with the stunt guys. I loved working with the camera guys. I loved the special-effects crew, and just putting together these logistically massive sequences. I don't know, I just got a real kick out of it. It was great.So it's something you would take on again.

Marshall: Oh, definitely. The one thing that I think unites all my films is a strong action element, and that's what I love filming. That's what I love doing. So no, it was a pleasure to do all that stuff.So were there any tough days? Or was it all fun?

Marshall: I don't know. It's such a difficult thing to say, because I love making films so much. There's always challenges, but it's overcoming the challenges that's the issue. Every day is a challenge. Trying to meet the schedule is a challenge. Trying to keep it within the budget is a challenge, but you do it. And I enjoy that challenge.Do you have a sequence that turned out to be your favorite?

Marshall: We did this huge sequence, it was inside this huge auditorium and we had a thousand extras, we had this whole musical stage number—big fat guys in kilts doing the cancan, pole dancers, human sacrifice, this whole thing with fire and props and all kinds of craziness.So it was like a ritual of some kind?

Marshall: It's halfway between Moulin Rouge and The Wicker Man, like some weird combination. I got my wife in the movie. She makes a cameo appearance in that scene. It was just great. It was this huge scene, which I thought was going to be a nightmare, and it wasn't. It was a pleasure. It was a joy. Basically, I put my lead actor on stage and he just ran the show. He just did his speech and the whole performance and the audience reacted to him. And I just had to step back and film the whole thing once we'd set it up, because I knew that he's a stage actor, so I knew that he was going to be able to pull it off. So we just created the environment and shot it. It was great.You mentioned Moulin Rouge and Wicker Man. What were some of your other film influences for this?

Marshall: Well, I've said from the start that this film is hugely inspired by the likes of Mad Max and Escape From New York and The Warriors. And even things like the "Wild Boys" video by Duran Duran. It's that kind of anarchic style. They all came out around that time when everybody was doing post-apocalyptic stuff. "Two Tribes" and suchlike. So yeah, it's hugely inspired by that kind of stuff.You've clearly got your actors made up in that style.

Marshall: We utilized a lot of face paint, but it was more we wanted to do sort of tribal patterns and tattoos and scarring and things. We wanted them to look pretty fierce.Did that carry into the production design as well?

Marshall: Very much so. That was the starting point, but then we brought in so many other elements. We threw everything into the mix.And that is contrasted with the world on the other side of the wall, isn't it?

Marshall: Yeah. It's almost in direct contrast, in so many different elements. I mean, the production designers came up with so many different worlds within this story. And every one had to look totally different from the other. So there's so many elements that go into that.Did you always know you were going to get an R rating? Did that allow you to go for it in terms of the violence and harshness of the film?

Marshall: Well, I never held back at all. I wasn't necessarily going for a particular rating ever, but we never had to cut it. We got an R rating and I'm happy with that. So that's fine. Everybody's happy with that. So I certainly didn't hold back.How would you categorize this film?

Marshall: It's got so many different elements in it. If there's a genre that's post-apocalyptic, then it's definitely that. It's got horrific elements in it, but I wouldn't call it a horror movie. It's got sci-fi elements in it, but I wouldn't really call it a sci-fi movie, although it deals with the future. Primarily it's an action movie, but it's got a bit of everything in it.