THE most exhilarating and difficult times of his life await Harry Potter as he returns to Hogwarts School of Witchcraft and Wizardry for his fourth year of study in Harry Potter and the Goblet of Fire, the fourth film adaptation of J.K. Rowling's immensely popular series.

Not only must Harry compete in a dangerous international tournament that pits him against his older and more experienced peers, but he will also be forced to confront his nemesis, the evil Lord Voldemort, who is determined to return to power and finish Harry off once and for all.

This harrowing news pales only in comparison to Harry's genuine anxiety over having to find a date for Hogwarts' Yule Ball.

The school year will also bring significant changes for Harry's best friends Ron and Hermione, who may finally acknowledge a change in their feelings for each other.

"Much to her surprise, Hermione gets herself a boyfriend in Viktor Krum," says Emma Watson, who plays the female lead. "This proves to be a huge shock for Harry and Ron particularly Ron, who has only just realised that Hermione is a girl!"

"We've always had the sense that there is something growing between Ron and Hermione, although neither are really aware of it," muses Rupert Grint, who plays Ron. "In this film, both begin to admit it to themselves. When Hermione turns up at the Yule Ball with Viktor Krum, Ron finally realises that he has feelings for her."

"For me, the essence of this story is a thriller," says director Mike Newell. "There are wonderful set pieces, from the excitement of the Triwizard Tournament to the humour and heartbreak of the Yule Ball, but driving the story is this marvellous thriller in which something truly evil is out to get Harry and only he has the power to do something about it."

"What I really like about Harry is that he's not a hero in the classic sense, a brave all-conquering Superman," says Daniel Radcliffe, who watched thrillers like North by Northwest at director Mike Newell's suggestion in preparation for filming.

"Harry's vulnerable. He's scared. Even though he's helped so many people, I think he's always yearned to leave his past behind him and let the hero' thing end. But when his name comes out of the Goblet, he's instantly back in the limelight again. Not only does he have to cope with criticism from everyone, he also knows he didn't put his name in the Goblet so someone else must have."

When Harry turns to his trusted mentor for guidance and protection, he is surprised to discover that Dumbledore himself is struggling to uncover the meaning of these mysterious events.

"Dumbledore is no longer in control and he's frightened," says Michael Gambon, who reprises his role as the highly-respected Hogwarts' headmaster in Harry Potter and the Prisoner of Azkaban. "He carries tremendous weight on his shoulders, ensuring the safety and well-being of the students, and when evil penetrates Hogwarts, he doesn't know how to deal with it."

Suspecting that whoever put Harry's name in the Goblet didn't intend for him to win the Tournament, Dumbledore asks Alastor "Mad-Eye" Moody (Brendan Gleeson), Hogwarts' eccentric new Defence Against the Dark Arts teacher, to keep his highly perceptive eye trained on the teenage wizard until they discover the true meaning of these ominous events.

Gleeson says: "Moody is a gunslinger with a wand. He's someone who has chased the demons away from goodness to the extent that he's gotten quite warped by it."

Ralph Fiennes, who plays Lord Voldemort, says: ""Mike (Newell) was very keen to explore Voldemort's unexpected mood swings, his explosive rage. There are moments when anger spits out of him at Harry and other moments when he can be almost pleasant. You never quite know what he's going to do.

"People are incredibly scary when they're charming but you suspect they might suddenly do something very violent," he continues. "If you sit across the table from someone who offers you a glass of wine and a present, but you know that he stabbed his wife to death, it's quite unnerving."