But it was visible only for a split second. As though the creature beneath the cloak sensed Harry’s gaze, the hand was suddenly withdrawn into the folds of its black cloak.

And then the thing beneath the hood, whatever it was, drew a long, slow, rattling breath, as though it were trying to suck something more than air from its surroundings.

An intense cold swept over them all. Harry felt his own breath catch in his chest. The cold went deeper than his skin. It was inside his chest, it was inside his very heart…

Harry’s eyes rolled up into his head. He couldn’t see. He was drowning in cold. There was a rushing in his ears as though of water. He was being dragged downward, the roaring growing louder…

And then, from far away, he heard screaming, terrible, terrified, pleading screams. He wanted to help whoever it was, he tried to move his arms, but couldn’t…a thick white fog was swirling around him, inside him —

“Harry! Harry! Are you all right?”

Someone was slapping his face.

“W-what?”

Harry opened his eyes; there were lanterns above him, and the floor was shaking — the Hogwarts Express was moving again and the lights had come back on. He seemed to have slid out of his seat onto the floor. Ron and Hermione were kneeling next to him, and above them he could see Neville and Professor Lupin watching. Harry felt very sick; when he put up his hand to push his glasses back on, he felt cold sweat on his face.

Ron and Hermione heaved him back onto his seat.

“Are you okay?” Ron asked nervously.

“Yeah,” said Harry, looking quickly toward the door. The hooded creature had vanished. “What happened? Where’s that — that thing? Who screamed?”

“No one screamed,” said Ron, more nervously still.

Harry looked around the bright compartment. Ginny and Neville looked back at him, both very pale.

“But I heard screaming —”

A loud snap made them all jump. Professor Lupin was breaking an enormous slab of chocolate into pieces.

“Here,” he said to Harry, handing him a particularly large piece. “Eat it. It’ll help.”

Harry took the chocolate but didn’t eat it.

“What was that thing?” he asked Lupin.

“A Dementor,” said Lupin, who was now giving chocolate to everyone else. “One of the Dementors of Azkaban.”

Everyone stared at him. Professor Lupin crumpled up the empty chocolate wrapper and put it in his pocket.

“Eat,” he repeated. “It’ll help. I need to speak to the driver, excuse me…”

He strolled past Harry and disappeared into the corridor.

“Are you sure you’re okay, Harry?” said Hermione, watching Harry anxiously.

“I don’t get it … what happened?” said Harry, wiping more sweat off his face.

“Well — that thing — the Dementor — stood there and looked around (I mean, I think it did, I couldn’t see its face) — and you — you —”

“I thought you were having a fit or something,” said Ron, who still looked scared. “You went sort of rigid and fell out of your seat and started twitching —”

“And Professor Lupin stepped over you, and walked toward the Dementor, and pulled out his wand,” said Hermione, “and he said, ‘None of us is hiding Sirius Black under our cloaks. Go.’ But the Dementor didn’t move, so Lupin muttered something, and a silvery thing shot out of his wand at it, and it turned around and sort of glided away…”

“It was horrible,” said Neville, in a higher voice than usual. “Did you feel how cold it got when it came in?”

“I felt weird,” said Ron, shifting his shoulders uncomfortably. “Like I’d never be cheerful again…”

Ginny, who was huddled in her corner looking nearly as bad as Harry felt, gave a small sob; Hermione went over and put a comforting arm around her.

“But didn’t any of you — fall off your seats?” said Harry awkwardly.

“No,” said Ron, looking anxiously at Harry again. “Ginny was shaking like mad, though…”

Harry didn’t understand. He felt weak and shivery, as though he were recovering from a bad bout of flu; he also felt the beginnings of shame. Why had he gone to pieces like that, when no one else had?

Professor Lupin had come back. He paused as he entered, looked around, and said, with a small smile, “I haven’t poisoned that chocolate, you know…”

Harry took a bite and to his great surprise felt warmth spread suddenly to the tips of his fingers and toes.

“We’ll be at Hogwarts in ten minutes,” said Professor Lupin. “Are you all right, Harry?”

Harry didn’t ask how Professor Lupin knew his name.

“Fine,” he muttered, embarrassed.

They didn’t talk much during the remainder of the journey. At long last, the train stopped at Hogsmeade station, and there was a great scramble to get outside; owls hooted, cats meowed, and Neville’s pet toad croaked loudly from under his hat. It was freezing on the tiny platform; rain was driving down in icy sheets.

“Firs’ years this way!” called a familiar voice. Harry, Ron, and Hermione turned and saw the gigantic outline of Hagrid at the other end of the platform, beckoning the terrified-looking new students forward for their traditional journey across the lake.

“All right, you three?” Hagrid yelled over the heads of the crowd. They waved at him, but had no chance to speak to him because the mass of people around them was shunting them away along the platform. Harry, Ron, and Hermione followed the rest of the school along the platform and out onto a rough mud track, where at least a hundred stagecoaches awaited the remaining students, each pulled, Harry could only assume, by an invisible horse, because when they climbed inside and shut the door, the coach set off all by itself, bumping and swaying in procession.

The coach smelled faintly of mold and straw. Harry felt better since the chocolate, but still weak. Ron and Hermione kept looking at him sideways, as though frightened he might collapse again.

As the carriage trundled toward a pair of magnificent wrought iron gates, flanked with stone columns topped with winged boars, Harry saw two more towering, hooded Dementors, standing guard on either side. A wave of cold sickness threatened to engulf him again; he leaned back into the lumpy seat and closed his eyes until they had passed the gates. The carriage picked up speed on the long, sloping drive up to the castle; Hermione was leaning out of the tiny window, watching the many turrets and towers draw nearer. At last, the carriage swayed to a halt, and Hermione and Ron got out.

As Harry stepped down, a drawling, delighted voice sounded in his ear.

“You fainted, Potter? Is Longbottorn telling the truth? You actually fainted?”

Malfoy elbowed past Hermione to block Harry’s way up the stone steps to the castle, his face gleeful and his pale eyes glinting maliciously.

“Shove off, Malfoy,” said Ron, whose jaw was clenched.

“Did you faint as well, Weasley?” said Malfoy loudly. “Did the scary old Dementor frighten you too, Weasley?”

“Is there a problem?” said a mild voice. Professor Lupin had just gotten out of the next carriage.

Malfoy gave Professor Lupin an insolent stare, which took in the patches on his robes and the dilapidated suitcase. With a tiny hint of sarcasm in his voice, he said, “Oh, no — er — Professor ,” then he smirked at Crabbe and Goyle and led them up the steps into the castle.

Hermione prodded Ron in the back to make him hurry, and the three of them joined the crowd swarming up the steps, through the giant oak front doors, into the cavernous Entrance Hall, which was lit with flaming torches, and housed a magnificent marble staircase that led to the upper floors.

The door into the Great Hall stood open at the right; Harry followed the crowd toward it, but had barely glimpsed the enchanted ceiling, which was black and cloudy tonight, when a voice called, “Potter! Granger! I want to see you both!”

Harry and Hermione turned around, surprised. Professor McGonagall, Transfiguration teacher and head of Gryffindor House, was calling over the heads of the crowd. She was a stern looking witch who wore her hair in a tight bun; her sharp eyes were framed with square spectacles. Harry fought his way over to her with a feeling of foreboding: Professor McGonagall had a way of making him feel he must have done something wrong.

“There’s no need to look so worried — I just want a word in my office,” she told them. “Move along there, Weasley.”

Ron stared as Professor McGonagall ushered Harry and Hermione away from the chattering crowd; they accompanied her across the entrance hall, up the marble staircase, and along a corridor.

Once they were in her office, a small room with a large, welcoming fire, Professor McGonagall motioned Harry and Hermione to sit down. She settled herself behind her desk and said abruptly, “Professor Lupin sent an owl ahead to say that you were taken ill on the train, Potter.”

Before Harry could reply, there was a soft knock on the door and Madam Pomfrey, the nurse, came bustling in.

Harry felt himself going red in the face. It was bad enough that he’d passed out, or whatever he had done, without everyone making all this fuss.

“I’m fine,” he said, “I don’t need anything —”

“Oh, it’s you, is it?” said Madam Pomfrey, ignoring this and bending down to stare closely at him. “I suppose you’ve been doing something dangerous again?”

“It was a Dementor, Poppy,” said Professor McGonagall.

They exchanged a dark look, and Madam Pomfrey clucked disapprovingly.

“Setting Dementors around a school, she muttered, pushing back Harry’s hair and feeling his forehead. “He won’t be the last one who collapses. Yes, he’s all clammy. Terrible things, they are, and the effect they have on people who are already delicate —”

“I’m not delicate!” said Harry crossly.

“Of course you’re not,” said Madam Pomfrey absentmindedly, now taking his pulse.

“What does he need?” said Professor McGonagall crisply. “Bed rest? Should he perhaps spend tonight in the hospital wing?”

“I’m fine !” said Harry, jumping up. The thought of what Draco Malfoy would say if he had to go to the hospital wing was torture.

“Well, he should have some chocolate, at the very least,” said Madam Pomfrey, who was now trying to peer into Harry’s eyes.

“I’ve already had some,” said Harry. “Professor Lupin gave me some. He gave it to all of us.”

“Did he, now?” said Madam Pomfrey approvingly. “So we’ve finally got a Defense Against the Dark Arts teacher who knows his remedies?”