The chapter opens with the revelation that, following the pixie episode, Lockhart turned Defense Against the Dark Arts into Story Time. He now spends his class periods recounting his [[ExactWords incredible]] exploits, occasionally getting students (i.e. Harry) to help him reenact the dramatic parts. After the bell rings and Lockhart announces their homework of writing a poem about his supposed awesomeness, the Trio asks him to sign the permission form for ''Moste Potente Potions''. He cheerfully complies, not even bothering to look at what book they want.
After getting the book, our heroes head for the privacy of Moaning Myrtle's bathroom. Polyjuice Potion, as it turns out, is the most complicated potion Hermione has ever encountered and some of the ingredients are not available to students. At this point, Harry and Ron are getting cold feet, but then Hermione surprises both boys by for once siding ''against'' following the rules. After Harry and Ron are convinced to continue with the plan, Hermione calculates that the potion will take an entire month to make. "It'll be a lot less hassle if you can just knock Malfoy off his broom tomorrow," Ron tells Harry.
Indeed, the next day is the dreaded Quidditch match against Slytherin. Wood addresses Slytherin's advantage in his pep talk and tells Harry to get the Snitch first "[[SeriousBusiness or die trying]]". After the game starts, a Bludger immediately turns on Harry, refusing to leave him alone or attack any other players. The Weasley twins end up trailing Harry in an effort to protect him. Time out is called and everyone agrees that Bludger must have been sabotaged by cheating Slytherins, though they can't figure how. Harry insists Fred and George leave him alone so that he'll stand a chance of catching the Snitch. Most of the team protests, but Wood sides with Harry and orders the Weasleys off him. After play resumes, Harry catches the Snitch, but gets a broken arm for his trouble. Against Harry's wishes, Lockhart decides to "fix" his arm. With Harry in no state to resist, Lockhart does a spell which [[SarcasmMode surprisingly]] doesn't work right. Instead of repairing the bones, it removes them. Harry is brought to the hospital wing where Madam Pomfrey is livid. After all, she could have cured Harry's broken arm in a second, but now he will have to take a disagreeable potion called Skele-Gro and spend the night in the hospital growing back the bones in his arm.
That night Harry is woken up by Dobby. Dobby admits that he stopped Harry and Ron from catching the train and that he was responsible for the rogue Bludger -- all in an effort to keep Harry safely away from Hogwarts. Harry is not touched by the gesture. Dobby reveals more details of his unenviable life, including the fact that house-elves can only be set free when they are given proper clothes, and accidentally lets slip that the Chamber of Secrets has been opened before. He Disapparates (which he can do on Hogwarts grounds because house-elf magic is, of course, ''completely different'' from wizard magic) when footsteps are heard approaching. Harry pretends to sleep as Dumbledore and [=McGonagall=] enter carrying the Petrified body of Colin Creevey. [=McGonagall=] gets Madam Pomfrey and Dumbledore opens Colin's camera, hoping he might have gotten a picture of his attacker, but finds the film is melted. Dumbledore says this means the Chamber is indeed open again and that "the question is not ''who''. The question is, ''how''..."