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Harry Potter and the Half-Blood Prince

J. K. Rowling
  • Study Guide

Chapters 20 and 21

Summary Chapters 20 and 21


At their next lesson, Dumbledore asks Harry if he was able to retrieve the memory from Slughorn. Harry has not done so but promises to try harder. Dumbledore is extremely disappointed. They return to studying Voldemort. Dumbledore explains how Voldemort had been an excellent student. Many faculty members suggested that he apply for a position at the Ministry after graduation. Instead, Voldemort asked if he might remain at Hogwarts as an instructor of Defense against the Dark Arts. Then-Headmaster Dippet told Voldemort that he was too young but should consider reapplying later. Voldemort took a job working at Borgin and Burkes, persuading people to part with Dark or unusual objects. Harry and Dumbledore enter the Pensieve to view a memory of Hokey, a House Elf to a very rich old witch named Hepzibah Smith.

Hepzibah is enthralled by Voldemort and offers to show him two extremely rare objects, a small golden cup and a locket. Hephzibah tells Voldemort that the cup belonged to Helga Hufflepuff, one of the four founders of Hogwarts. The gold locket bears Slytherin’s mark and is the same locket that Merope sold to Borgin and Burkes many years earlier. Voldemort’s eyes turn scarlet as Hepzibah explains how she bought the locket from the shop and refuses to give it up. Harry and Dumbledore return to Hogwarts. Dumbledore explains that Hepzibah Smith died days after the visit they witnessed, supposedly poisoned by Hokey, who later confessed to the crime. Harry and Dumbledore agree that Voldemort must have murdered Hepzibah and changed Hokey’s memory so that she would confess to the crime. After Hokey was convicted, Hepzibah’s family realized that the locket and the cup were missing. Around the same time, Voldemort left his job at Borgin and Burkes and was not seen or heard from for a very long time. Dumbledore notes that Voldemort has now committed another murder, this time killing for gain rather than revenge.

The next memory they witness is one of Dumbledore’s, from ten years after Hepzibah’s death. Dumbledore is seated in his office at Hogwarts when Voldemort knocks and enters. Voldemort reminds Dumbledore that he no longer goes by the name Tom Riddle. Voldemort again expresses his interest in teaching Defense Against the Dark Arts, but Dumbledore is skeptical and denies him. Harry and Dumbledore return to Dumbledore’s present-day office. Dumbledore reminds Harry that ever since he denied Voldemort the position of Defense Against the Dark Arts professor, Hogwarts has not been able to keep a Defense teacher longer than one year. Later, Harry finds a new spell, Sectumsempra, scrawled in the margins of his Potions textbook, with the words “For Enemies.” Kreacher and Dobby reappear to report back. Dobby tells Harry that while Draco is not breaking any rules, he makes regular trips to the seventh floor, bringing other students with him to stand guard. Harry remembers the Room of Requirement on the seventh floor, which transforms into whatever its transformer requires.

Harry decides to sneak up on Draco when he is in the Room of Requirement, but Hermione reminds him that unless he knows exactly what Draco is doing, he cannot summon the Room, because he won’t know what he needs it to be. Kreacher and Dobby leave. Harry thinks Draco must have stolen some Polyjuice Potion from Slughorn and has been using it on Crabbe and Goyle, transforming them into first-year girls to avoid suspicion.

The next weekend, Ron and Hermione go to Hogsmeade to practice Apparition. After they leave, Harry attempts to get into the Room of Requirement to see what Draco is doing. After thirty minutes of trying, Harry still cannot gain access to the room. Frustrated, Harry rushes at the wall. His Invisibility Cloak slips off, and Tonks suddenly appears, looking thin and haggard. Tonks asks Harry if he’s heard from any members of the Order, but Harry explains that since Sirius’s death, no one writes to him anymore. Tonks’s eyes fill with tears. Later, Harry tells his friends about running into Tonks and that he suspects she may have been in love with Sirius.


Dumbledore believes that Voldemort was interested in teaching at Hogwarts because of the proximity the position would offer to strong magic and young, impressionable wizards. But Dumbledore also thinks that, as an orphan, Voldemort considered Hogwarts his only real home. Harry has always felt similarly, having long despised living with his horrible aunt, uncle, and cousin, where magic was not allowed to be discussed or alluded to. When Harry came to Hogwarts five years ago, it was the first time he ever felt like he had a real home, with a real family. Once again, Harry observes a similarity between his own trajectory and Voldemort’s history. Rowling is careful to emphasize that although Harry and Voldemort came from extremely similar origins, and were forced to deal with equally terrible childhoods, Harry has never been tempted to give in to the Dark Arts. Again, Harry’s remarkable heart seems to be what prevents him from sharing Voldemort’s tragic fate.