Professor Dumbledore sent all the Gryffindors back to the Great Hall, where they were joined ten minutes later by the students from Hufflepuff, Ravenclaw, and Slytherin, who all looked extremely confused.

“The teachers and I need to conduct a thorough search of the castle,” Professor Dumbledore told them as Professors McGonagall and Flitwick closed all doors into the hall. “I’m afraid that, for your own safety, you will have to spend the night here. I want the prefects to stand guard over the entrances to the hall and I am leaving the Head Boy and Girl in charge. Any disturbance should be reported to me immediately,” he added to Percy, who was looking immensely proud and important. “Send word with one of the ghosts.”

Professor Dumbledore paused, about to leave the hall, and said, “Oh, yes, you’ll be needing…”

One casual wave of his wand and the long tables flew to the edges of the hall and stood themselves against the walls; another wave, and the floor was covered with hundreds of squashy purple sleeping bags.

“Sleep well,” said Professor Dumbledore, closing the door behind him.

The hall immediately began to buzz excitedly; the Gryffindors were telling the rest of the school what had just happened.

“Everyone into their sleeping bags!” shouted Percy. “Come on, now, no more talking! Lights out in ten minutes!”

“C’mon,” Ron said to Harry and Hermione; they seized three sleeping bags and dragged them into a corner.

“Do you think Black’s still in the castle?” Hermione whispered anxiously.

“Dumbledore obviously thinks he might be,” said Ron.

“It’s very lucky he picked tonight, you know,” said Hermione as they climbed fully dressed into their sleeping bags and propped themselves on their elbows to talk. “The one night we weren’t in the tower…”

“I reckon he’s lost track of time, being on the run,” said Ron. “Didn’t realize it was Halloween. Otherwise he’d have come bursting in here.”

Hermione shuddered.

All around them, people were asking one another the same question: “How did he get in ?”

“Maybe he knows how to Apparate,” said a Ravenclaw a few feet away, “Just appear out of thin air, you know.”

“Disguised himself, probably,” said a Hufflepuff fifth year.

“He could’ve flown in,” suggested Dean Thomas.

“Honestly, am I the only person who’s ever bothered to read Hogwarts, A History ?” said Hermione crossly to Harry and Ron.

“Probably,” said Ron. “Why?”

“Because the castle’s protected by more than walls, you know,” said Hermione. “There are all sorts of enchantments on it, to stop people entering by stealth. You can’t just Apparate in here. And I’d like to see the disguise that could fool those Dementors. They’re guarding every single entrance to the grounds. They’d have seen him fly in too. And Filch knows all the secret passages, they’ll have them covered…”

“The lights are going out now!” Percy shouted. “I want everyone in their sleeping bags and no more talking!”

The candles all went out at once. The only light now came from the silvery ghosts, who were drifting about talking seriously to the prefects, and the enchanted ceiling, which, like the sky outside, was scattered with stars. What with that, and the whispering that still filled the hall, Harry felt as though he were sleeping outdoors in a light wind.

Once every hour, a teacher would reappear in the Hall to check that everything was quiet. Around three in the morning, when many students had finally fallen asleep, Professor Dumbledore came in. Harry watched him looking around for Percy, who had been prowling between the sleeping bags, telling people off for talking. Percy was only a short way away from Harry, Ron, and Hermione, who quickly pretended to be asleep as Dumbledore’s footsteps drew nearer.

“Any sign of him, Professor?” asked Percy in a whisper.

“No. All well here?”

“Everything under control, sir.”

“Good. There’s no point moving them all now. I’ve found a temporary guardian for the Gryffindor portrait hole. You’ll be able to move them back in tomorrow.”

“And the Fat Lady, sir?”

“Hiding in a map of Argyllshire on the second floor. Apparently she refused to let Black in without the password, so he attacked. She’s still very distressed, but once she’s calmed down, I’ll have Mr Filch restore her.”

Harry heard the door of the hall creak open again, and more footsteps.

“Headmaster?” It was Snape. Harry kept quite still, listening hard. “The whole of the third floor has been searched. He’s not there. And Filch has done the dungeons; nothing there either.”

“What about the Astronomy tower? Professor Trelawney’s room? The Owlery?”

“All searched…”

“Very well, Severus. I didn’t really expect Black to linger.”

“Have you any theory as to how he got in, Professor?” asked Snape.

Harry raised his head very slightly off his arms to free his other ear.

“Many, Severus, each of them as unlikely as the next.”

Harry opened his eyes a fraction and squinted up to where they stood; Dumbledore’s back was to him, but he could see Percy’s face, rapt with attention, and Snape’s profile, which looked angry.

“You remember the conversation we had, Headmaster, just before — ah — the start of term?” said Snape, who was barely opening his lips, as though trying to block Percy out of the conversation.

“I do, Severus,” said Dumbledore, and there was something like warning in his voice.

“It seems — almost impossible — that Black could have entered the school without inside help. I did express my concerns when you appointed —”

“I do not believe a single person inside this castle would have helped Black enter it,” said Dumbledore, and his tone made it so clear that the subject was closed that Snape didn’t reply. “I must go down to the Dementors,” said Dumbledore. “I said I would inform them when our search was complete.”

“Didn’t they want to help, sir?” said Percy.

“Oh yes,” said Dumbledore coldly. “But I’m afraid no Dementor will cross the threshold of this castle while I am Headmaster.”

Percy looked slightly abashed. Dumbledore left the hall, walking quickly and quietly. Snape stood for a moment, watching the headmaster with an expression of deep resentment on his face; then he too left.

Harry glanced sideways at Ron and Hermione. Both of them had their eyes open too, reflecting the starry ceiling.

“What was all that about?” Ron mouthed.

The school talked of nothing but Sirius Black for the next few days. The theories about how he had entered the castle became wilder and wilder; Hannah Abbott, from Hufflepuff, spent much of their next Herbology class telling anyone who’d listen that Black could turn into a flowering shrub.

The Fat Lady’s ripped canvas had been taken off the wall and replaced with the portrait of Sir Cadogan and his fat gray pony. Nobody was very happy about this. Sir Cadogan spent half his time challenging people to duels, and the rest thinking up ridiculously complicated passwords, which he changed at least twice a day.

“He’s a complete lunatic,” said Seamus Finnigan angrily to Percy. “Can’t we get anyone else?”

“None of the other pictures wanted the job,” said Percy. “Frightened of what happened to the Fat Lady. Sir Cadogan was the only one brave enough to volunteer.”

Sir Cadogan, however, was the least of Harry’s worries. He was now being closely watched. Teachers found excuses to walk along corridors with him, and Percy Weasley (acting, Harry suspected, on his mother’s orders) was tailing him everywhere like an extremely pompous guard dog. To cap it all, Professor McGonagall summoned Harry into her office, with such a somber expression on her face Harry thought someone must have died.

“There’s no point hiding it from you any longer, Potter,” she said in a very serious voice. “I know this will come as a shock to you, but Sirius Black —”

“I know he’s after me,” said Harry wearily. “I heard Ron’s dad telling his mum. Mr. Weasley works for the Ministry of Magic.”

Professor McGonagall seemed very taken aback. She stared at Harry for a moment or two, then said, “I see! Well, in that case, Potter, you’ll understand why I don’t think it’s a good idea for you to be practicing Quidditch in the evenings. Out on the field with only your team members, it’s very exposed, Potter —”

“We’ve got our first match on Saturday!” said Harry, outraged. “I’ve got to train, Professor!”

Professor McGonagall considered him intently. Harry knew she was deeply interested in the Gryffindor team’s prospects; it had been she, after all, who’d suggested him as Seeker in the first Place. He waited, holding his breath.

“Hmm…”Professor McGonagall stood up and stared out of the window at the Quidditch field, just visible through the rain. “Well…goodness knows, I’d like to see us win the Cup at last…but all the same, Potter…I’d be happier if a teacher were present. I’ll ask Madam Hooch to oversee your training sessions.”

The weather worsened steadily as the first Quidditch match drew nearer. Undaunted, the Gryffindor team was training harder than ever under the eye of Madam Hooch. Then, at their final training session before Saturday’s match, Oliver Wood gave his team some unwelcome news.

“We’re not playing Slytherin!” he told them, looking very angry. “Flint’s just been to see me. We’re playing Hufflepuff instead.”

“Why?” chorused the rest of the team.

“Flint’s excuse is that their Seeker’s arm’s still injured,” said Wood, grinding his teeth furiously. “But it’s obvious why they’re doing it. Don’t want to play in this weather. Think it’ll damage their chances…”

There had been strong winds and heavy rain all day, and as Wood spoke, they heard a distant rumble of thunder.

“There’s nothing wrong with Malfoy’s arm!” said Harry furiously. “He’s faking it!”

“I know that, but we can’t prove it,” said Wood bitterly, “And we’ve been practicing all those moves assuming we’re playing Slytherin, and instead it’s Hufflepuff, and their style’s quite different. They’ve got a new Captain and Seeker, Cedric Diggory —”

Angelina, Alicia, and Katie suddenly giggled.

“What?” said Wood, frowning at this lighthearted behavior.

“He’s that tall, good-looking one, isn’t he?” said Angelina.