“Staying here, Potter?” shouted Malfoy, who was standing in line with Crabbe and Goyle. “Scared of passing the dementors?”

Harry ignored him and made his solitary way up the marble staircase, through the deserted corridors, and back to Gryffindor Tower.

“Password?” said the Fat Lady, jerking out of a doze.

“Fortuna Major,” said Harry listlessly.

The portrait swung open and he climbed through the hole into the common room. It was full of chattering first and second years, and a few older students, who had obviously visited Hogsmeade so often the novelty had worn off.

“Harry! Harry! Hi, Harry!”

It was Colin Creevey, a second year who was deeply in awe of Harry and never missed an opportunity to speak to him.

“Aren’t you going to Hogsmeade, Harry? Why not? Hey”—Colin looked eagerly around at his friends—“you can come and sit with us, if you like, Harry!”

“Er—no, thanks, Colin,” said Harry, who wasn’t in the mood to have a lot of people staring avidly at the scar on his forehead. “I—I’ve got to go to the library, got to get some work done.”

After that, he had no choice but to turn right around and head back out of the portrait hole again.

“What was the point waking me up?” the Fat Lady called grumpily after him as he walked away.

Harry wandered dispiritedly toward the library, but halfway there he changed his mind; he didn’t feel like working. He turned around and came face-to-face with Filch, who had obviously just seen off the last of the Hogsmeade visitors.

“What are you doing?” Filch snarled suspiciously.

“Nothing,” said Harry truthfully.

“Nothing!” spat Filch, his jowls quivering unpleasantly. “A likely story! Sneaking around on your own—why aren’t you in Hogsmeade buying Stink Pellets and Belch Powder and Whizzing Worms like the rest of your nasty little friends?”

Harry shrugged.

“Well, get back to your common room where you belong!” snapped Filch, and he stood glaring until Harry had passed out of sight.

But Harry didn’t go back to the common room; he climbed a staircase, thinking vaguely of visiting the Owlery to see Hedwig, and was walking along another corridor when a voice from inside one of the rooms said, “Harry?”

Harry doubled back to see who had spoken and met Professor Lupin, looking around his office door.

“What are you doing?” said Lupin, though in a very different voice from Filch. “Where are Ron and Hermione?”

“Hogsmeade,” said Harry, in a would-be casual voice.

“Ah,” said Lupin. He considered Harry for a moment. “Why don’t you come in? I’ve just taken delivery of a grindylow for our next lesson.”

“A what?” said Harry.

He followed Lupin into his office. In the corner stood a very large tank of water. A sickly green creature with sharp little horns had its face pressed against the glass, pulling faces and flexing its long, spindly fingers.