Harry can’t believe it. The Weasley’s have invited him to the Quidditch World Cup, which means he’ll get to leave the Dursley’s house early and go see a game that anyone would kill to see.
The game is intense, but not just because of the stellar players and non-stop action. Voldemort’s servants, the Death Eaters, make an appearance and the wizarding world is shocked when Voldemort’s sign appears in the sky after the game.
When Harry, Ron, and Hermione finally make it back to Hogwarts a few weeks later, they’re shocked to find that the school will be hosting the Triwizard Tournament this year. It’s a competition between the three wizarding schools of Hogwarts, Durmstrang, and Beauxbatons. A champion is chosen for each school and competes in very difficult challenges that test their skill and daring.
When the students from the other schools arrive in October, the students begin putting their name in the Goblet of Fire in order to be chosen as their school's champion. Harry is shocked beyond belief when, in spite of his inability to compete because of his age, he’s chosen as the fourth school champion.
What’s even worse is that Ron doesn’t believe that Harry didn’t put his name in the goblet. They get into a huge fight, and Ron stops talking to Harry. The rest of Hogwarts is also incensed that Harry is "looking for more fame", and the only person who stands by Harry’s side is Hermione.
In the tournament, the first task of fighting dragons goes great for Harry, and what’s even better is that it convinces Ron that Harry was telling the truth all along, and they become friends again.
As the school year progresses Harry is beset with troubles. Snooping journalist, Rita Skeeter, continues to publish gossipy articles about Harry that alienate him from the rest of the school, he’s turned down by his crush, Cho Chang, when he asks her to the Yule Ball, and in the days leading up to the second task of the tournament, which involves retrieving something important from the bottom of a lake filled with mer-people, he almost doesn’t find a way to accomplish what he’s got to do. Saved at the last minute, however, Harry again gets almost full marks and is tied for first place.
Sirius returns to keep an eye on Harry, as well as the mysterious happenings that keep taking place at Hogwarts. There is someone at the school who wants Harry dead, but no one knows who it is.
During the final task of the tournament, Harry and Cedric both tie for first place, but as soon as they grasp the winner's cup, they are transported to a creepy graveyard where Cedric is immediately killed and Harry tied up by Wormtail. He witnesses Voldemort’s return to power, and barely makes it back to Hogwarts alive, clutching Cedric’s body.
When he gets back he discovers that "Professor Moody",the new Defense Against the Dark Arts teacher, was the traitor all along. He’s a magically disguised Death Eater who risked everything to kidnap Harry for Lord Voldemort. Harry tells Dumbledore what happened with Voldemort, and although the Minister of Magic, Cornelius Fudge, doesn’t believe Harry, Professor Dumbledore begins to take steps to mobilize against Voldemort.