Harry Potter and the Half-Blood Prince: Chapter Twenty-One: The Unknowable Room Summary & Analysis

For the next week, Harry wonders how he can achieve success with Slughorn. He takes to leafing through his Potions book for advice, even though Hermione thinks it has nothing useful to say. Ignoring her, he notices an incantation labeled “for enemies” and earmarks the page. The trio are sitting in the Gryffindor common room, finishing homework and fretting over their upcoming Apparition tests.

Hermione argues that if Dumbledore thinks only Harry can acquire the memory, the task has to do with his personal characteristics, not with figuring out some obscure spell or potion. She turns her attention to Ron, whose quill is malfunctioning and causing him to spell every word wrong. She begins magically correcting his essay while he lies back tiredly, saying he loves her. Tersely, she warns him not to let Lavender hear things like this. Ron says he hopes she does; then she’ll ditch him rather than clinging to him like a “giant squid.”

When everyone has gone to bed except the trio, Kreacher and Dobby suddenly appear in the common room. Harry hasn’t told Hermione about his investigations, since she strongly disapproves of house-elf labor; indeed, she’s incensed that, because Harry casually told them to follow Draco around the clock, they haven’t slept in a week. Kreacher praises Draco’s bearing and “nobility,” but Dobby says that Malfoy is often “keen to avoid detection” and uses many other students to keep watch while he sneaks into the Room of Requirement. Harry realizes that this is why he hasn’t been able to see Draco on the map.

It’s impossible for Dobby to get into the Room of Requirement without knowing why Draco is using it, so Harry releases the elves for now. Hermione kindly commends Kreacher on his work, but he calls her a Mudblood before disappearing. Hermione wonders why Draco is using so many different students as lookouts – but suddenly Harry realizes that Draco has been simply using Slughorn’s Polyjuice Potion to disguise Crabbe and Goyle. The small girls who have appeared with Draco, as well as the student whose scales Hermione repaired, were actually his sidekicks in disguise.

Before going to bed, Hermione reminds Harry that his job is to get Slughorn’s memory, not track Draco. Still, he lies awake all night wondering why Draco is using the Room of Requirement. The next day, he decides to follow him during his free period; after all, he still has no idea how to approach Slughorn, so he might as well use this time productively. At breakfast, Hermione reports several new attacks and the imprisonment of Mundungus Fletcher for burglary.

Under the Invisibility Cloak, Harry approaches the Room of Requirement and paces outside of it, thinking determinedly that he needs to see what it becomes for Draco. However, no matter how many formulations of this request he tries, no door reveals itself in the wall. Arriving late to Defense Against the Dark Arts he loses ten points for Gryffindor and is taunted by Snape for insufficiently answering a question on the difference between ghosts and Inferi.

Trying to ditch Lavender after class, Ron and Harry duck into a bathroom, where they run into Moaning Myrtle. She’s disappointed to see them, having expected another boy who had promised to visit her. Ron is amused by the idea of Myrtle having a crush on someone, but Myrtle resentfully says that she has a lot of common with him: they’re both sensitive and have been bullied, and they both cry in the bathroom sometimes. When Ron insults her again, she vanishes in disgust.

That weekend, Ron and Hermione go to Hosgmeade for additional Apparition practice. Since he can’t take the test until he turns seventeen later in the summer, Harry tries to enter the Room of Requirement again – even though Hermione insists he should talk to Slughorn instead. Under the Invisibility Cloak, Harry frightens Goyle away from the wall where he’s standing guard; but he’s again unable to gain entry to the room.

Just as he’s losing hope, Harry sees Tonks walking towards him. He’s surprised to find her in the castle, but she says she’s come to see Dumbledore, who’s away. She absentmindedly asks if he’s heard from anyone in the Order recently, but when Harry says he hasn’t gotten mail since Sirius dies her eyes fill with tears and she strides away. When Ron and Hermione return from practice, Harry tells them of this strange encounter. He wonders aloud if she was in love with Sirius – after all, any mention of him upsets her and her Patronus is something furry and four-legged, not unlike his dog form.

Hermione is still confused as to why Tonks is coming to visit Dumbledore instead of remaining at her station in Hogsmeade. Ron shrugs and says that women are “easily upset.” Hermione sharply points out that Ron is the one who spent the morning sulking because Madam Rosmerta didn’t laugh at his stupid joke.