Voldemort and his Death Eaters openly wreak havoc throughout Britain. Following public outcry over his mishandling the Voldemort situation, Minister for Magic Cornelius Fudge is forced to resign and is succeeded by Rufus Scrimgeour. As a result, Arthur Weasley receives a promotion.

At his home in Spinner's End, Severus Snape is visited by Draco Malfoy's mother Narcissa and her sister, Bellatrix Lestrange. Although Bellatrix distrusts Snape, Narcissa swears him to an Unbreakable Vow, ensuring he will protect Draco during his task assigned by the Dark Lord and, should her son fail, complete his mission for the Dark Lord.

Albus Dumbledore arrives at the Dursleys' and asks Harry Potter to accompany him to see retired professor Horace Slughorn. With unwitting help from Harry, Dumbledore persuades Slughorn to resume his old teaching post at Hogwarts. Harry then spends the remaining summer months at The Burrow with the Weasleys and Hermione, who is also visiting. To his family's dismay, Bill Weasley has become engaged to Fleur Delacour, the Beauxbatons champion in the Triwizard Tournament. As Harry spends time with Ginny, he begins experiencing romantic feelings for her. Harry, Ron, and Hermione receive their O.W.L. results. Hermione receives high marks in all her subjects, but Ron and Harry fail Divination and History of Magic. To become Aurors, they need to take N.E.W.T.-level Potions as a prerequisite, but Snape only accepts "O" (Outstanding) grades, ending Harry's career ambitions. While shopping in Diagon Alley for school supplies, Harry, Ron and Hermione spot Draco Malfoy sneaking into Knockturn Alley. They follow and spy him entering Borgin & Burkes, a dark magic shop. Malfoy harasses Mr Borgin about repairing one item and keeping another safe for him.