Ron was not unique in this respect; interest in the Gryffindor-Ravenclaw game was running extremely high throughout the school, for the match would decide the Championship, which was still wide open. If Gryffindor beat Ravenclaw by a margin of three hundred points (a tall order, and yet Harry had never known his team to fly better) then they would win the Championship. If they won by less than three hundred points, they would come second to Ravenclaw; if they lost by a hundred points they would be third behind Hufflepuff and if they lost by more than a hundred, they would be in fourth place and nobody, Harry thought, would ever, ever let him forget that it had been he who had captained Gryffindor to their first bottom-of-the-table defeat in two centuries.

The run-up to this crucial match had all the usual features: members of rival Houses attempting to intimidate opposing teams in the corridors; unpleasant chants about individual players being rehearsed loudly as they passed; the team members themselves either swaggering around enjoying all the attention or else dashing into bathrooms between classes to throw up. Somehow, the game had become inextricably linked in Harry’s mind with success or failure in his plans for Ginny. He could not help feeling that if they won by more than three hundred points, the scenes of euphoria and a nice loud after-match party might be just as good as a hearty swig of Felix Felicis.

In the midst of all his preoccupations, Harry had not forgotten his other ambition: finding out what Malfoy was up to in the Room of Requirement. He was still checking the Marauder’s Map, and as he was unable to locate Malfoy on it, deduced that Malfoy was still spending plenty of time within the room. Although Harry was losing hope that he would ever succeed in getting inside the Room of Requirement, he attempted it whenever he was in the vicinity, but no matter how he reworded his request, the wall remained firmly doorless.

A few days before the match against Ravenclaw, Harry found himself walking down to dinner alone from the common room, Ron having rushed off into a nearby bathroom to throw up yet again, and Hermione having dashed off to see Professor Vector about a mistake she thought she might have made in her last Arithmancy essay. More out of habit than anything, Harry made his usual detour along the seventh-floor corridor, checking the Marauder’s Map as he went. For a moment he could not find Malfoy anywhere and assumed he must indeed be inside the Room of Requirement again, but then he saw Malfoy’s tiny, labeled dot standing in a boys’ bathroom on the floor below, accompanied, not by Crabbe or Goyle, but by Moaning Myrtle.

Harry only stopped staring at this unlikely coupling when he walked right into a suit of armor. The loud crash brought him out of his reverie; hurrying from the scene lest Filch turn up, he dashed down the marble staircase and along the passageway below. Outside the bathroom, he pressed his ear against the door. He could not hear anything. He very quietly pushed the door open.

Draco Malfoy was standing with his back to the door, his hands clutching either side of the sink, his white-blond head bowed.

“Don’t,” crooned Moaning Myrtle’s voice from one of the cubicles. “Don’t… tell me what’s wrong… I can help you…”

“No one can help me,” said Malfoy. His whole body was shaking. “I can’t do it… I can’t… It won’t work… and unless I do it soon… he says he’ll kill me…”

And Harry realized, with a shock so huge it seemed to root him to the spot, that Malfoy was crying — actually crying — tears streaming down his pale face into the grimy basin. Malfoy gasped and gulped and then, with a great shudder, looked up into flu-cracked mirror and saw Harry staring at him over his shoulder.

Malfoy wheeled around, drawing his wand. Instinctively, Harry pulled out his own. Malfoy’s hex missed Harry by inches, shattering the lamp on the wall beside him; Harry threw himself sideways, thought Levicorpus! and flicked his wand, but Malfoy blocked the jinx and raised his wand for another —

“No! No! Stop it!” squealed Moaning Myrtle, her voice echoing loudly around the tiled room. “Stop! STOP!”

There was a loud bang and the bin behind Harry exploded; Harry attempted a Leg-Locker Curse that backfired off the wall behind Malfoy’s ear and smashed the cistern beneath Moaning Myrtle, who screamed loudly; water poured everywhere and Harry slipped as Malfoy, his face contorted, cried, “Cruci —”

“SECTUMSEMPRA!” bellowed Harry from the floor, waving his wand wildly.

Blood spurted from Malfoy’s face and chest as though he had been slashed with an invisible sword. He staggered backward and collapsed onto the waterlogged floor with a great splash, his wand falling from his limp right hand.

“No —” gasped Harry.

Slipping and staggering, Harry got to his feet and plunged toward Malfoy, whose face was now shining scarlet, his white hands scrabbling at his blood-soaked chest.

“No — I didn’t —”

Harry did not know what he was saying; he fell to his knees beside Malfoy, who was shaking uncontrollably in a pool of his own blood. Moaning Myrtle let out a deafening scream: “MURDER! MURDER IN THE BATHROOM! MURDER!”

The door banged open behind Harry and he looked up, terrified: Snape had burst into the room, his face livid. Pushing Harry roughly aside, he knelt over Malfoy, drew his wand, and traced it over the deep wounds Harry’s curse had made, muttering an incantation that sounded almost like song. The flow of blood seemed to ease; Snape wiped the residue from Malfoy’s face and repeated his spell. Now the wounds seemed to be knitting.

Harry was still watching, horrified by what he had done, barely aware that he too was soaked in blood and water. Moaning Myrtle was still sobbing and wailing overhead. When Snape had performed his countercurse for the third time, he half-lifted Malfoy into a standing position.

“You need the hospital wing. There may be a certain amount of scarring, but if you take dittany immediately we might avoid even that… Come…”

He supported Malfoy across the bathroom, turning at the door to say in a voice of cold fury, “And you, Potter… You wait here for me.”

It did not occur to Harry for a second to disobey. He stood up slowly, shaking, and looked down at the wet floor. There were bloodstains floating like crimson flowers across its surface. He could not even find it in himself to tell Moaning Myrtle to be quiet, as she continued to wail and sob with increasingly evident enjoyment.

Snape returned ten minutes later. He stepped into the bathroom and closed the door behind him.

“Go,” he said to Myrtle, and she swooped back into her toilet at once, leaving a ringing silence behind her.

“I didn’t mean it to happen,” said Harry at once. His voice echoed in the cold, watery space. “I didn’t know what that spell did.”

But Snape ignored this. “Apparently I underestimated you, Potter,” he said quietly. “Who would have thought you knew such Dark Magic? Who taught you that spell?”

“I — read about it somewhere.”

“Where?”

“It was — a library book,” Harry invented wildly. “I can’t remember what it was call —”

“Liar,” said Snape. Harry’s throat went dry. He knew what Snape was going to do and he had never been able to prevent it…

The bathroom seemed to shimmer before his eyes; he struggled to block out all thought, but try as he might, the Half-Blood Prince’s copy of Advanced Potion-Making swam hazily to the forefront of his mind.

And then he was staring at Snape again, in the midst of this wrecked, soaked bathroom. He stared into Snape’s black eyes, hoping against hope that Snape had not seen what he feared, but —

“Bring me your schoolbag,” said Snape softly, “and all of your schoolbooks. All of them. Bring them to me here. Now!”

There was no point arguing. Harry turned at once and splashed out of the bathroom. Once in the corridor, he broke into a run toward Gryffindor Tower. Most people were walking the other way; they gaped at him, drenched in water and blood, but he answered none of the questions fired at him as he ran past.

He felt stunned; it was as though a beloved pet had turned suddenly savage; what had the Prince been thinking to copy such a spell into his book? And what would happen when Snape saw it? Would he tell Slughorn — Harry’s stomach churned — how Harry had been achieving such good results in Potions all year? Would he confiscate or destroy the book that had taught Harry so much… the book that had become a kind of guide and friend? Harry could not let it happen… He could not…

“Where’ve you — ? Why are you soaking — ? Is that blood.” Ron was standing at the top of the stairs, looking bewildered at , the sight of Harry.

“I need your book,” Harry panted. “Your Potions book. Quick… give it to me…”

“But what about the Half-Blood —”

“I’ll explain later!”

Ron pulled his copy of Advanced Potion-Making out of his bag and handed it over; Harry sprinted off past him and back to the common room. Here, he seized his schoolbag, ignoring the amazed looks of several people who had already finished their dinner, threw himself back out of the portrait hole, and hurtled off along the seventh-floor corridor.

He skidded to a halt beside the tapestry of dancing trolls, closed his eyes, and began to walk.

I need a place to hide my book… I need a place to hide my book… I need a place to hide my book…

Three times he walked up and down in front of the stretch of blank wall. When he opened his eyes, there it was at last: the door to the Room of Requirement. Harry wrenched it open, flung him self inside, and slammed it shut.

He gasped. Despite his haste, his panic, his fear of what awaited him back in the bathroom, he could not help but be overawed by what he was looking at. He was standing in a room the size of a large cathedral, whose high windows were sending shafts of light down upon what looked like a city with towering walls, built of what Harry knew must be objects hidden by generations of Hogwarts inhabitants. There were alleyways and roads bordered by tetering piles of broken and damaged furniture, stowed away, perhaps, to hide the evidence of mishandled magic, or else hidden by castle-proud house-elves. There were thousands and thousands of books, no doubt banned or graffitied or stolen. There were winged catapults and Fanged Frisbees, some still with enough life in them to hover halfheartedly over the mountains of other forbidden items; there were chipped bottles of congealed potions, hats, jewels, cloaks; there were what looked like dragon eggshells, corked bottles whose contents still shimmered evilly, several rusting swords, and a heavy, bloodstained axe.