To intensify the already dark story in the book, Newell added a few flourishes. Harry isn't just trying to get around a dragon to steal its egg; now, the dragon breaks free and chases him all around Hogwarts.
"In this one shot during the dragon chase," Newell says, "He's knocked off his broom and slides down a very steep roof, which Daniel did for real. He slid 30 feet — on a safety wire, of course. But nobody had to say, 'Sorry, Dan, you've got to do it.' "
"The flamethrower thing was kind of cool," Daniel says, "just because there was fire, which is always interesting. But falling down the roof? Hmmm. That was insane! I can't believe I lived through that."
Newell also upgraded the book's enchanted maze. Instead of having to fight creatures within it, the contestants have to fight the maze itself, a labyrinth (with hydraulically operated walls) that can swallow them whole.
"No one knew if it would kill you or not if you got trapped in there, so it was enforced method acting," says Robert Pattinson, who plays Cedric Diggory, one of Harry's Triwizard rivals. "It was really claustrophobic and confusing. Everyone had loads of cuts and bruises from those walls."
An underwater rescue scene, however, didn't need to be tinkered with to make it any more difficult or scarier for the cast members, and even those who were being rescued, as opposed to those doing the actual rescuing, had to learn to scuba dive to prepare for the murky waters of the Black Lake. Stanislav Ianevski, who plays Viktor Krum, another Triwizard rival, had two weeks of professional training with the coach for the British Olympic diving team, for a dive that was later cut from the film. ("I was afraid of the water when I started," he says. "The first time I went under, I was breathing really heavily, and when you do that under water, you start getting dizzy.") Katie Leung, who plays Harry's love interest Cho Chang, bruised her inner ear a few times before learning to blow out the air pressure the right way.
But Daniel got the worst of it, since he started out as a "rotten swimmer" and had to train for six months in the 60-foot tank for his more extensive scenes.
"That was hard work, actually," Daniel says. "I would go under there, and I was sharing somebody's air from their scuba diving tank. And they'd say, 'Three, two, one,' and on the 'Three,' I'd blow out all the air in my lungs, and then on the 'One,' I'd take a very big gulp of air. Then it's [a matter of] how much action can you do with that amount of breath in your body. The hard thing wasn't holding your breath — it's the fact that you can't let any air out because Harry's supposed to have become a fish, with gills, so there's not supposed to be any bubbles around. So if I look at all pained …"
Forced into a tournament with tasks he has no choice but to attempt — it's a binding magical contract, after all — Harry forces himself to be brave, even though he doesn't feel up to the task at all. And Daniel, too, forced himself to be brave, Newell says, despite being "absolutely terrified."
"I don't think he's naturally going to turn into a stunt man, but he will read himself the riot act, he will tell himself what he's got to do," Newell says. "He knows what he must do and he simply does it."
"When we began, on the first film, Dan was not a physical boy," producer David Heyman says. "And now he's a jock, of sorts. We put him together with our stunt team, and his body has changed. At lunch several times a week, he'll go down to the gym and work out. It's not something we're asking him to do."
But it's what it takes to be Harry Potter, which is only going to get harder as the story progresses. Daniel's already preparing for "Order of the Phoenix," which starts shooting in February with, yes, yet another new director, a Briton named David Yates, known in the U.K. for his work on a politically charged 2003 miniseries called "State of Play." Under Yates' guidance, Daniel's exploring what will be Harry's emotional aftermath from "Goblet," by meeting with a bereavement counselor so he could understand survivor's guilt.
Harry's two main relationships in "Phoenix" — with his godfather Sirius Black (Gary Oldman) and new girlfriend Cho Chang — are both grounded in a mutual need to bond with another person after a great, shared loss.
"Sirius is clinging on to James [Harry's father and Sirius' best friend] through me, and I'm trying to know my father through him," Daniel says, "and the same thing happens with me and Cho. I was the last person there when her last boyfriend, Cedric, was killed."
Cedric's murder at the end of "Goblet" is a turning point for the series — it's the moment where Harry can't save the day, where being good or having magic isn't enough. If anything, his failure teaches him to be more of a hero than ever before, but the call to arms that follows awaits them in "Phoenix." And yes, all three of the main kids will be back for that; fans need not assume, or fear, that they're outgrowing their roles just because the films are taking longer to shoot. ("Goblet" took 11 months, while "Phoenix" isn't expected to be out until 2007, with "Half Blood Prince" not arriving sooner than 2008).
"It actually works out really well, because each film takes about a year, and that coincides with us doing our year at school, so we're growing alongside our characters," insists Emma, who's 15. Plus, "people play a lot younger than they actually are in real life," points out Daniel, who's 16.
And will the three leads actually stick with the series right up to the concluding seventh film?
"There is so much of me that goes into Hermione now," Watson admits, "that if anybody else played her, it would kill me."