"Harry Potter and the Goblet of Fire" is the fourth book in J.K. Rowling's Harry Potter series. The novel follows the eponymous character's fourth year at Hogwarts School of Witchcraft and Wizardry and the ominous events that precede and unfold during the Triwizard Tournament, a magical competition between the three largest European wizarding schools.
The book starts with a departure from the usual Harry-at-the-Dursleys introduction. Instead, it opens with the murder of Frank Bryce, a Muggle gardener, at the hands of Voldemort and his servant Peter Pettigrew (Wormtail) in the Riddle house in Little Hangleton. Voldemort is discussing plans to kill Harry with Pettigrew and an unknown individual.
Harry wakes up with a painful scar from a dream he's had about this conversation. He's at the Dursleys for the summer, but soon he's rescued by the Weasleys, who take him to the Quidditch World Cup along with Hermione. At the event, Death Eaters (Voldemort's followers) cause chaos, and someone conjures Voldemort's Dark Mark using Harry's wand.
When Harry returns to Hogwarts, he learns about the Triwizard Tournament. Students aged seventeen and above from Beauxbatons, Durmstrang, and Hogwarts are eligible to participate. Although Harry is underage and doesn't submit his name, the Goblet of Fire inexplicably selects him as an additional champion alongside Cedric Diggory from Hogwarts, Viktor Krum from Durmstrang, and Fleur Delacour from Beauxbatons.
The tournament comprises three tasks designed to test the champions' magical prowess, courage, and resourcefulness. The first task involves retrieving a golden egg from a dragon. Despite the danger, Harry accomplishes this with the help of Hagrid, Hermione, and the unwitting assistance of Barty Crouch, Sr., a high-ranking Ministry of Magic official who suggested using a summoning charm.
During the second task, Harry must rescue his friend Ron from underwater creatures in the Hogwarts lake. He also ends up helping Fleur to save her sister, demonstrating his integrity.
Meanwhile, Harry experiences troubling dreams about Voldemort, which seem to indicate that Voldemort is becoming stronger. Barty Crouch, Sr. disappears, and Harry finds Crouch's deranged house-elf, Winky, in the Forbidden Forest.
In the third and final task, champions must navigate through a dangerous maze to reach the Triwizard Cup. Harry and Cedric reach the cup simultaneously and decide to touch it together, declaring a draw. However, the cup turns out to be a Portkey that transports them to a graveyard where Voldemort is waiting.
Voldemort orders Pettigrew to kill Cedric and then uses Harry's blood to regain his full strength and corporeal form. He then summons the Death Eaters and reveals that his faithful servant at Hogwarts ensured Harry's participation in the tournament and guided him to the cup. Voldemort then duels Harry, but their wands share twin cores (both having feathers from the same phoenix, Fawkes), causing a phenomenon known as "Priori Incantatem." This causes the spirits of Voldemort's recent victims, including Cedric and Harry's parents, to appear and momentarily distract Voldemort, allowing Harry to escape back to Hogwarts with Cedric's body using the Portkey.
Upon their arrival, it's revealed that the faithful servant mentioned by Voldemort is Barty Crouch Jr., who had been disguising himself as Mad-Eye Moody, the Defense Against the Dark Arts teacher, using Polyjuice Potion. The real Moody was imprisoned in a magical trunk. Crouch Jr. confesses under the influence of Veritaserum that he guided Harry through the tournament with the aim of delivering him to Voldemort. He also admits to placing Harry's name in the Goblet of Fire and manipulating events so that Harry would win the tournament and touch the Triwizard Cup, which he had turned into a Portkey. Barty Crouch Jr. is then sent back to Azkaban, the wizarding prison, and the real Moody is freed.
The aftermath of these events is grim. Harry is profoundly affected by Cedric's death and his encounter with Voldemort. Hogwarts, once a sanctuary for Harry, has lost its sense of security. Despite the evidence, the Ministry of Magic, particularly its head Cornelius Fudge, refuses to believe that Voldemort has returned, leading to a split between the Ministry and Hogwarts.
Harry gives his Triwizard Tournament prize money to Fred and George Weasley to help them start their joke shop, as per his promise to Cedric's memory (Cedric had helped him during the tournament). He then returns to Privet Drive for the summer, where he must grapple with the trauma of what he has experienced.
The events of "Harry Potter and the Goblet of Fire" represent a significant turning point in the series. The tone of the series becomes significantly darker after this book, as the wizarding world is no longer the safe haven it once seemed to Harry. He must now prepare for the inevitable confrontation with Voldemort, who has returned to full strength. As such, "Goblet of Fire" sets the stage for the escalating conflict in the remaining books of the series.