When he returns, Moody takes him to his office, and reveals himself to be Voldemort's 'faithful servant'; he was the one who put Harry's name into the Goblet of Fire, and has been guiding him through the tournament from behind the scenes to ensure that he would grab the Portkey first. Before Moody can kill Harry, Dumbledore, McGonagall and Snape intervene. They learn that Moody is in fact Barty Crouch Jr., Mr. Crouch's son, disguised by Polyjuice Potion. Crouch had sentenced Crouch Jr. to life imprisonment in Azkaban over alleged ties to the Death Eaters but smuggled him out as a last favour to his dying wife. Crouch Jr. was the one who set off the Dark Mark at the Quidditch World Cup, doing it to scare the Death Eaters he felt had abandoned Voldemort. Eventually, Voldemort had gotten in contact with Crouch Jr. and had him impersonate Moody as part of his plan. Crouch Jr. also admits to killing Crouch Sr., to prevent him telling Dumbledore about Voldemort. The real Moody is found inside Crouch Jr.'s enchanted trunk and rescued. Harry is then declared the winner of the Triwizard Tournament and given his winnings.
Many people, including Fudge, do not believe Harry and Dumbledore about Voldemort's return, and as Fudge has the Dementor's Kiss performed, Crouch Jr. is unable to give testimony. Hermione discovers Rita Skeeter is an unregistered Animagus, who can take the form of a beetle, and blackmails her to force her to stop writing her libellous stories. Not wanting his tournament winnings, Harry gives them to Fred and George to start their joke shop and returns home with the Dursleys.