"If there were craft services, it probably wouldn't be the film that it is," says Heather Donahue, who, along with her costars Joshua Leonard and Michael Williams, endured physical discomfort, head games, and food and sleep deprivation in the making of The Blair Witch Project. "But I have not had a Powerbar since, and I probably never will again," she says, laughing. "After hiking for six miles during the course of the day, I'd be like, 'Hmm, I'm a pretty well-trained actress. Is this really necessary? I'm hungry, dammit.' And when you're tired and cold and snug in your sleeping bag and it's 35 degrees outside, and there are these Haxan boys running around in the woods snapping twigs, you're kind of like, 'This may be a noble effort, but I really don't feel like getting up.' "

These perfectly understandable complaints aside, the 24-year-old Donahue insists she would "do it again in a heartbeat," noting that Blair Witch counts as a genuine rarityâ€" a conceptual piece with built-in challenges for the actors. "It's interesting as an actor to be put in a situation where you can't anticipate or plan what you're going to do in a scene, and you just have to react," she says. "You can't decide, oh, I think this scene would be a great one to smack the tree and go real crazy. It's not about you; it's about how all three of you interact, and about being open to that process."

The improvisatory nature of the project was, she says, evident from the first audition. "As soon as I sat down, Dan Myrick, one of the directors, said to me, 'Well, you've served seven years of a 25-year sentence, why do you think we should let you out on parole?' And I was like, 'You know, I don't think you should.' And we just went from there, rolled with it, nobody missed a beat." Auditions dragged on for about a year, as Donahue acknowledges, casting was "pretty crucial. You want people who can not only handle it physically and emotionally but also be willing to continue to handle it."

The movie, an exercise in first-person terror, posed technical challenges, too, requiring that the performers double as cinematographers. "I'd never operated a camera before," says Donahue. "We had a two-day crash film course. I learned how to load the 16mm camera. I learned how to work the Hi-8 video camera. But I didn't really get it all in two days, which is why the camera is superjumpy at some points."

In the absence of a script, the actors were given no more information than they needed to get through the next scene. "We had no idea what they had in store for us a few days down the line, or how it was going to end. Every day, we would find our way to these wait points that had been programmed into our GPS [Global Positioning System] devices. And waiting for us would be three little film cans, one for each of us, with our initials on it. We weren't allowed to show each other the instructions, which would be things like, 'When you get to the pine forest make sure the camera is on,' or, 'Let Mike hold the compass today.' "

The three spent seven straight days in the woods, surfacing only once during that period. "We were hiking with these 60-pound packs and it had rained for 24 straight hours so we used the escape routes that the directors had programmed into the GPS devices, and we ended up at a house in the woods. Much to our surprise, this couple let us in and made us hot cocoa. We got to use a toilet and all these wonderful things that we had forgotten about for a few days."

Donahue is, however, keen to stress that the methods weren't as sadistic as they might sound. "Nothing was hidden from us. We didn't know specifically what was going to happen, but we knew the types of situations that we'd be put in. As Gregg Hale, the producer, said to us, 'Your safety is our issue, your comfortability is not.' But I have to say we were actually better looked after than on some indie productions that I've been on. They had to, otherwise everything would have fallen apart."

During filming, the directors kept their distance but remained within reach. "At night they were camped a hundred yards north of us, and if we ever needed them we had a CB radio. We also had a code word between us actors, which was taco, which we would use whenever we felt like breaking the scenario. But even when we did that, the dynamic was similar to the one we'd established as characters. We were thrown into our characters and these extreme situations and all of this insanity right off the bat and none of us really got to know each other. Not until now do we get to see what we're each really like. And when we see each other for press stuff, it's like, oh wow, you're pretty cool, I could hang out with you."

Donahue says she modeled her character, the strong-minded, verging on pigheaded, leader of the trio, on a director she once worked with. "A lot of people know someone like that. It's a study of an amateur in production, a portrait of a student filmmaker, male or female. I've done student films, and I know these people. I know what they're like, they think they know exactly how it's going to go down, but when it comes time to compromise or work out an alternate way of doing things, they become completely frazzled. They can't listen to anyone because they're so afraid of failure. It's really pretty funny in retrospect, but when you're dealing with that person at the time it's not so hilarious."

Donahue, who admits to being "a big overpreparer," says she did "tons" of research. "I was reading up on witchcraft, documentary filmmaking, cinematography, and also on survival. They made it sound like I was going to be skinning and roasting squirrels for food, so I'd prepared myself for the absolute worst. I bought all these books, I had The Army Survival Book, I had How To Stay Alive in the Woods, I was learning how to start a fire with a drop of water and a needle. As it turned out, it was definitely not as bad as I'd anticipated. All that preparation also went into building the character."

The filmmakers were no less obsessive. "They sent us all these elaborate, completely fictional brochures about Blair County, the hunting season, the annual zucchini festival, full- color pictures of this smiling blond girl holding an armful of zucchinis. They really went out of their way to create a whole world, down to every last detail."

This attention to detail has already created a cult around the film. Donahue says she's thrilled by the reception, but adds, deadpan, "I do worry a little bit about some of the fans who might go out into the woods and take a gag too far. I hope people take all necessary safety precautions in trying to scare the shit out of their friends."