Diggory has put a strong team together and is an excellent player himself and both of these facts worry Oliver Wood. Diggory catches the Snitch just after Harry falls off his broomstick, ensuring Hufflepuff's win. When he realises Harry has fallen however, he tries to call a re-match, but the Hufflepuff victory stands.
Cedric is an extremely handsome boy of around seventeen. He and his father, Amos Diggory, are using the Portkey on Stoatshead Hill to travel to the Quidditch World Cup. They had to leave their home at 2 o'clock in the morning to get to the Portkey location in time. He is embarassed when his father boasts about Cedric beating Harry in a Quidditch match the previous year, and tries to remind him once again that it was an accident, as Harry fell off his broom, with little effect.
Cedric, Arthur and Amos are the only ones of the group who land on their feet after the Portkey delivers them to the campsite.
Harry overhears Ernie Macmillan wondering whether Cedric knows when the delegations from Beauxbatons and Durmstrang will arrive, and assumes that Cedric must be entering his name for consideration as the Hogwarts Triwizard champion.
Cedric stands by the fire in the room off the Great Hall with Fleur Delacour and Viktor Krum. He looks nonplussed when Ludo Bagman introduces Harry as the fourth Triwizard champion. He looks back and forth between Harry and Bagman, as though sure he has misheard what Bagman just said.
Cedric smiles slightly as he and Harry make their way through the Great Hall, amused that they are once again competing against one another. He asks Harry how he got his name into the Goblet of Fire, and doesn't believe Harry when he denies the charge.
The majority of the Hogwarts students support Cedric as the true Hogwarts champions. The Slytherin students go so far as to wear badges supporting the Hufflepuff student. Cedric finds himself the centre of much attention during the days following the announcement of the Triwizard champions; he is accosted by several sixth-year girls begging him to sign their schoolbags one lunchtime.
Cedric stands talking to Fleur Delacour when Harry enters the classroom for the Wand Weighing ceremony. He is the second champion to have his wand tested. Cedric's wand is twelve and a quarter inches, pleasantly springy and made of ash, and contains a single unicorn hair. He keeps his wand in good condition, and tells Ollivander he polished it the night before.
Cedric makes his way from the Great Hall towards the Charms corridor after breakfast on Monday morning. His bag splits as he reaches the corridor, causing bits of parchment, quills and books to spill onto the floor. Cedric is exasperated that his new bag has broken, unaware that it was magically split by Harry. Cedric is surprised when Harry walks up to him and tells him that the first task of the Triwizard Tournament will involve dragons and wants to know how Harry found out. He is confused as to why Harry has told him and looks slightly suspicious about the information.
Cedric paces around the champions' tent as they wait for the first task to begin. He picks the Swedish Short-Snout dragon from the bag Ludo Bagman produces, and is assigned to be the first champion to do the task. He looks greener than ever as he makes his way from the tent towards the dragon enclosure. Ron tells Harry that Cedric Transfigured a rock on the ground into a dog to try to distract his dragon. He managed to get the egg but got burnt as well, as the dragon changed its mind halfway through and decided it would rather have Cedric than the labrador.
Cedric sits in the first-aid tent after he has completed the task. He is injured but doesn't appear to be very badly hurt.
Cedric attends the Yule Ball with Cho Chang. Later in the evening, Cedric catches up to Harry on the stairs in the Entrance Hall. He tells Harry that he owes him for Harry's clue about the dragons, and cryptically tells Harry to take a bath with the egg, and to mull things over in the hot water. He suggests that Harry use the Prefects' bathroom, and gives him the password. He grins after giving Harry the clue, and hurries back down the stairs to say goodnight to Cho.
Cedric stands by the judges' table at the lake waiting for Harry to arrive, and the second task to begin. Cedric uses the Bubble-Head Charm to allow him to breath underwater. He is the first champion to arrive at the statue of the merperson after Harry, and quickly pulls out a knife to cut Cho Chang free. He pulls her upwards and swims out of sight. Cedric is on the shore, wrapped in blankets, when Harry arrives back with Ron and Gabrielle. Cedric was the first champion to return with their hostage, although he returned one minute outside the time limit. He is awarded forty-seven points for the task, and is in tied first place with Harry after the second task.
Cedric joins Harry in the Entrance Hall on their way to the Quidditch pitch. Cedric is horrified when he sees the changes to the Quidditch pitch, noticing the long, low hedges that are growing all over it. He and Harry make their way towards the middle of the pitch to join Ludo Bagman, Fleur Delacour and Viktor Krum, with less than happy expressions on their faces. After Bagman tells the champions about the third task, Cedric makes his way back towards the castle.
Cedric is greeted by his parents in the chamber off the Great Hall on the morning of the third task. He apologises to Harry for his father's behaviour, aware that Amos has been angry since Rita Skeeter's article implied Harry was the only Hogwarts champion.
After the evening feast, Cedric walks with the other champions to the Quidditch pitch in preparation for the third task. Cedric enters the maze at the same time as Harry, ahead of Fleur Delacour and Viktor Krum, in accordance with their number of awarded points. After about fifty yards, the boys reach a fork in the maze; the boys separate, with Cedric taking the right-hand path. Cedric encounters Hagrid's enlarged Blast-Ended Skrewts in the maze, and barely manages to get away from them. During the third task, Cedric is hit with the Cruciatus Curse, performed by Viktor Krum. His screams fill the air as he is tortured with the curse. He shakes as he is rescued by Harry, shocked at the unexpected behaviour of the Durmstrang champion. He and Harry send red sparks in the air to mark Krum's location, then continue on their way. Cedric spots the Triwizard Cup soon after, and begins to sprint towards it. He is warned by Harry of the giant spider that appears on his left, but trips and drops his wand as he hurls himself aside to avoid the creature. Cedric manages to regain his wand with Harry's help, and the pair eventually defeat the spider. Although he is able to reach the Triwizard Cup ahead of the injured Harry, Cedric is reluctant to do so. He stares at Harry and the Cup, unwilling to take first place for the task when he doesn't believe he deserves it. He tells Harry that without his help before the first task, he would not have made it this far, and admits that he had help with the golden egg. Cedric encourages Harry to grab the Cup first, but eventually agrees that they should both touch the Cup at the same time to ensure a joint win for Hogwarts. The boys grasp the handles of the Cup at the same time, and are transported away from the maze by the unexpected Portkey.
Cedric and Harry fall to the ground as they reach the destination of the Triwizard Cup Portkey. Cedric is confused about where they are, and wonders why they weren't told the Cup was a Portkey. He glances about the graveyard nervously, pulling out his wand. He and Harry watch as a short figure walks towards them, carrying something in its arms. He shoots Harry a quizzical look, before turning back to watch the figure approach. As the figure stops six feet from them, a high, cold voice says 'Kill the spare'; there is a blast of green light as a second voice performs the Killing Curse, killing Cedric instantly. He lies spread-eagled on the ground beside Harry, his open grey eyes blank and expressionless, a slightly surprised look on his face.
A shadowy figure of Cedric emerges from the end of Voldemort's wand amid screams of pain as the effects of Harry and Voldemort's wands connecting takes place. The ghostly Cedric pushes himself out of the wand, standing up and looking at the golden thread of light. He tells Harry to hold on, his voice distant and echoing. Cedric paces around the inner walls of the golden web with the shadows of Frank Bryce and Bertha Jorkins. Before Harry breaks the golden thread, Cedric asks Harry to take his body back to Hogwarts, to his parents. When Harry breaks the bond between his and Voldemort's wand, the shadowy figures of Voldemort's victims close in upon Voldemort, shielding Harry from his gaze. Cedric's body is carried back to Hogwarts via the Portkey alongside Harry.
Cedric's body is brought back to Hogwarts with Harry via the Portkey. He is protected by Harry, who is reluctant to let go of the boy in his shock, but the two are eventually separated.
Cedric was told by Barty Crouch Junior, who was disguised as Professor Moody, to open the golden egg underwater. Crouch knew that Cedric would want to repay Harry for his help with the first task, and so would pass on the information.
Out of respect for Cedric's memory, the Great Hall is not decorated in its usual fashion for the Leaving Feast following the Triwizard Tournament. The wall behind the teachers' table is covered with black drapes instead. Dumbledore toasts the memory of Cedric during his speech, and says that Cedric exemplified many of the qualities that distinguish Hufflepuff house. Dumbledore praises Cedric as a good and loyal friend, a hard worker and someone who valued fair play. It is revealed during the speech that Cedric was murdered by Lord Voldemort, and the students are encouraged to remember Cedric's death if ever there comes a time when they have to make a choice between what is right, and what is easy.