Hermione didn't turn up for the next class and wasn't seen all afternoon. On their way down to the Great Hall for the Halloween feast, Harry and Ron overheard Parvati Patil telling her friend Lavender that Hermione was crying in the girls’ bathroom and wanted to be left alone. Ron looked still more awkward at this, but a moment later they had entered the Great Hall, where the Halloween decorations put Hermione out of their minds.

A thousand live bats fluttered from the walls and ceiling while a thousand more swooped over the tables in low black clouds, making the candles in the pumpkins stutter. The feast appeared suddenly on the golden plates, as it had at the start-of-term banquet.

Harry was just helping himself to a baked potato when Professor Quirrell came sprinting into the hall, his turban askew and terror on his face. Everyone stared as he reached Professor Dumbledore's chair, slumped against the table, and gasped, “Troll — in the dungeons — thought you ought to know.”

He then sank to the floor in a dead faint.

There was an uproar. It took several purple firecrackers exploding from the end of Professor Dumbledore's wand to bring silence.

“Prefects,” he rumbled, “lead your Houses back to the dormitories immediately!”

Percy was in his element.

“Follow me! Stick together, first years! No need to fear the troll if you follow my orders! Stay close behind me, now. Make way, first years coming through! Excuse me, I'm a prefect!”

“How could a troll get in?” Harry asked as they climbed the stairs.

“Don't ask me, they're supposed to be really stupid,” said Ron. “Maybe Peeves let it in for a Halloween joke.”

They passed different groups of people hurrying in different directions. As they jostled their way through a crowd of confused Hufflepuffs, Harry suddenly grabbed Ron's arm.

“I've just thought — Hermione.”

“What about her?”

“She doesn't know about the troll.”

Ron bit his lip.

“Oh, all right,” he snapped. “But Percy'd better not see us.”

Ducking down, they joined the Hufflepuffs going the other way, slipped down a deserted side corridor, and hurried off toward the girls’ bathroom. They had just turned the corner when they heard quick footsteps behind them.

“Percy!” hissed Ron, pulling Harry behind a large stone griffin.

Peering around it, however, they saw not Percy but Snape. He crossed the corridor and disappeared from view.

“What's he doing?” Harry whispered. “Why isn't he down in the dungeons with the rest of the teachers?”

“Search me.”