“And time’s… up!” called Slughorn. “Stop stirring, please!”

Slughorn moved slowly among the tables, peering into cauldrons. He made no comment, but occasionally gave the potions a stir or a sniff. At last he reached the table where Harry, Ron, Hermione, and Ernie were sitting. He smiled ruefully at the tarlike substance in Ron’s cauldron. He passed over Ernie’s navy concoction. Hermione’s potion he gave an approving nod. Then he saw Harry’s, and a look of incredulous delight spread over his face.

“The clear winner!” he cried to the dungeon. “Excellent, excellent, Harry! Good lord, it’s clear you’ve inherited your mother’s talent. She was a dab hand at Potions, Lily was! Here you are, then, here you are — one bottle of Felix Felicis, as promised, and use it well!”

Harry slipped the tiny bottle of golden liquid into his inner pocket, feeling an odd combination of delight at the furious looks on the Slytherins’ faces and guilt at the disappointed expression on Hermione’s. Ron looked simply dumbfounded.

“How did you do that?” he whispered to Harry as they left the dungeon.

“Got lucky, I suppose,” said Harry, because Malfoy was within earshot.

Once they were securely ensconced at the Gryffindor table for dinner, however, he felt safe enough to tell them. Hermione’s face became stonier with every word he uttered.

“I s’pose you think I cheated?” he finished, aggravated by her expression.

“Well, it wasn’t exactly your own work, was it?” she said stiffly.

“He only followed different instructions to ours,” said Ron, “Could’ve been a catastrophe, couldn’t it? But he took a risk and it paid off.” He heaved a sigh. “Slughorn could’ve handed me that book, but no, I get the one no one’s ever written on. Puked on, by the look of page fifty-two, but-”

“Hang on,” said a voice close by Harry’s left ear and he caught a sudden waft of that flowery smell he had picked up in Slughorn’s dungeon. He looked around and saw that Ginny had joined them. “Did I hear right? You’ve been taking orders from something someone wrote in a book, Harry?”

She looked alarmed and angry. Harry knew what was on her mind at once.

“It’s nothing,” he said reassuringly, lowering his voice. “It’s not like, you know, Riddle’s diary. It’s just an old textbook someone’s scribbled on.”

“But you’re doing what it says?”

“I just tried a few of the tips written in the margins, honestly, Ginny, there’s nothing funny -”

“Ginny’s got a point,” said Hermione, perking up at once. “We ought to check that there’s nothing odd about it. I mean, all these funny instructions, who knows?”

“Hey!” said Harry indignantly, as she pulled his copy of Advanced Potion-Making out of his bag and raised her wand. “Specialis Revelio!” she said, rapping it smartly on the front cover. Nothing whatsoever happened. The book simply lay there, looking old and dirty and dog-eared.

“Finished?” said Harry irritably. “Or d’you want to wait and see if it does a few backflips?”

“It seems all right,” said Hermione, still staring at the book suspiciously. “I mean, it really does seem to be… just a textbook.”

“Good. Then I’ll have it back,” said Harry, snatching it off the table, but it slipped from his hand and landed open on the floor. Nobody else was looking. Harry bent low to retrieve the book, and as he did so, he saw something scribbled along the bottom of the back cover in the same small, cramped handwriting as the instructions that had won him his bottle of Felix Felicis, now safely hidden inside a pair of socks in his trunk upstairs.

This book is the property of the Half Blood Prince.