"So, Pete," said Sirius, once they'd reached the top of the staircase. "You need to find Filch and tell him that Remus and I are smashing up the Charms classroom."

"We're- we're not actually going to smash it up, are we?" asked Remus biting his lip. "We're just going to pretend, right?"

But Sirius only laughed and clapped Remus on the shoulder. "Pretend? What good would pretending do? We need to keep Filch distracted and the only way to do that is by making a mess."

"But Professor Flitwick will be angry."

Laughing again, Sirius shook his head at his friend. "You're hilarious when you act all innocent, Remus. Of course he's going to be angry. But that doesn't matter, does it? Not if we get to follow Filch and find some secret passageways."

"But- but..." Remus seemed to be struggling to grasp the idea. "Can't we smash up a corridor instead of a classroom?" he asked desperately.

Peter glanced at Sirius, knowing that he wouldn't back down. He was obviously the kind of person who goes all-out when it comes to mayhem. "I'd just go with it, Remus, if I were you," he said wisely and Sirius threw him a surprised look.

"Since when have you been eager to do something like this?"

"I'm not doing it, though, am I?" Peter pointed out. "So I don't have to worry about getting in trouble. I don't really care what you do."

Remus sighed. "Thanks, Pete," he said sarcastically, rolling his eyes. "It's great to know that you have my best interests at heart."

Peter flashed a toothy grin. "Sorry," he said meekly. "I'm just looking at things from a bystander's point of view. Sirius is right - it would make more of a distraction if it's a classroom."

"Yeah, Remus," added Sirius, now nodding vigorously. "And, let's face it, I could've picked McGonagall's classroom to smash up. Flitwick, on the other hand, won't be too angry; he likes you and Lily."

"Oh, that makes me feel so much better!" snapped Remus. Then he sighed again and began to walk down the corridor. "Come on, then. Let's just get this over with."

"I'll go and find Filch," said Peter, turning away from the other two so he could head in the opposite direction. "I think he went towards the Trophy Room. He's probably trying to keep an eye on Peeves. He's always in there."

"See you," called Sirius, watching Peter disappear.

"Yeah, we'll see you if we ever get out of this alive," said Remus darkly, giving Peter a gloomy wave.

Peter waved back, and Sirius turned to Remus.

"Oh, come on, Rems. Don't be so dramatic. We'll be fine. The most Filch can do is give us detention." He took his friend's arm and pulled him towards the Charms classroom, moving as quickly as possible without attracting suspicion. "When Filch turns up, I'll say it was my idea."

"Thanks, Sirius," said Remus gratefully, "But I don't want to force the blame on you."

"Well, technically, it was my idea," said Sirius brightly, as though taking the blame was nothing. He stopped outside the door. "Hey, look. This is it."

"Do you think Professor Flitwick will be inside?" asked Remus, looking anxious at the very idea.

Sirius shook his head. "Nah. It's a weekend. He'll probably be in the staff room." He put one hand on the doorknob and turned it, looking almost eager.

Remus peered over Sirius' head, just to check that their Charms teacher really wasn't in there. He sighed with relief when he saw that the classroom was empty.

Thank Merlin! He didn't think he'd be able to stand it if they had to distract someone else. Having to distract Filch was bad enough.

Pushing the door fully open, Sirius lead the way inside, glancing around as he did so. The classroom looked exactly the same as it had done during their last Charms lesson. Professor Flitwick's usual stack of books teetered behind the desk and one of the windows was open.

Remus blinked in the shaft of dusty sunlight that fell in from the grounds. It calmed him somewhat and he was able to follow Sirius to the front of the classroom.

He stopped moving, however, when he saw that Sirius had a huge, leather-bound book in his hands.

"Um, Sirius?" Remus whispered as he watched his friend leafing through the pages. "What are you doing?"

Sirius paused to look at a complicated-looking diagram. It showed a series of protective enchantments and their characteristics. "Looking through the books. What does it look like I'm doing?"

Hardly able to believe his ears, Remus stared at him. "Since when have you looked through books?"

"I wasn't reading them, stupid," said Sirius, rolling his eyes. "I was just seeing if they were valuable."

"Why?" asked Remus suspiciously. He didn't like the sound of this, especially not in their current situation. He wouldn't put it past Sirius to-

But he got no further along this line of thought. There was a sudden ripping sound, like a dragon tearing a person in half.

Remus gasped at the sight of torn, yellowing pages drifting to the floor in more pieces than he could count. It looked like confetti. "Oh, Merlin! Oh, my... Sirius, what- what are you...?"

Grinning broadly, Sirius ripped some more pages from the book and let them tumble. They fluttered through the air and landed at Remus' feet.

"Sirius, is that...? Is that...? You're actually ripping a book?" An odd, weak moan escaped from Remus' lips before he could stop it.

Sirius briefly glanced up. "Yep. Why're you asking? We're supposed to make a mess, aren't we?"

"But- but... But the book could be really precious. It could be ancient. It could be-"

"So? Flitwick can fix it, can't he? I'm only ripping it up. Why don't you start on those bookshelves over there?" He pointed to the shelf nearest to the door. "And, while you're at it, you could smash the window too..."

Knowing it was pointless to argue, Remus headed to the other side of the classroom and pulled out the newest-looking textbook he could find.

He was pretty sure that this one wasn't valuable, but still. It was a book.

He was going to rip a book.

He took a very deep breath and made a tiny tear in the first page, trying not to wince. Then he tore it a bit more, with the same pained expression on his face.

Behind him, Sirius was laughing.

Remus gritted his teeth, took hold of a whole handful of pages and pulled. They came out in his hand, just as they'd done for Sirius, and he scattered them on the floor, skirting around them so he didn't step on any.

Then, unable to bear it any longer, he crossed to the window, picked up a solid-looking set of scales and, summoning up his courage, threw it at the glass.

SMASH!

Transparent fragments flew everywhere, settling like shards of ice on the wooden flooring.

Sirius whooped loudly and stooped to pick up something heavy but, before he could throw it, the classroom door flew open.

The second bout of laughter died in Sirius' throat as he caught sight of four people standing in the doorway.

Flanked by Professor McGonagall, Filch and Peter, the tall form of Albus Dumbledore stared down at them over his half-moon spectacles. Professor McGonagall's lips were so thin that, for a moment, Sirius thought they'd disappeared.

Filch was shaking.

Feeling as though all the air had been knocked out of him, Remus staggered backwards and felt his cheeks burn. He seemed to have forgotten how to talk.

Why had he let Sirius and Peter talk him into this?

For a moment, nobody moved. Then Peter, looking pale and frightened, looked at Sirius. He opened his mouth to say something, but Professor Dumbledore got there first.

His silver hair and beard streaming over his star-patterned robes, he glanced from Remus to Sirius and said, "Please explain why you did this."

Professor McGonagall shook her head at them.

Sirius felt some of the shock melt away. He swallowed hard and looked into the headmaster's blue eyes. They weren't twinkling as they were known to do, but - for some strange reason - they didn't look angry either.

"I- I..." he began, staring down at his shoes. "We... We were..." He cleared his throat, remembering his promise to Remus. "It was my fault. I persuaded Remus to do it. It wasn't supposed to be horrible or mean. It was just a... a... a distraction."

Sirius could feel Dumbledore's gaze still on him and had the vague impression that he was being thoroughly examined. He tried to look ashamed of himself.

At last, however, Dumbledore fixed his piercing look on Remus instead. "A distraction?" he asked, looking down his crooked nose, while Remus trembled all over. "From what?"

"From- from..." Remus couldn't seem to keep his voice steady. The room was oddly blurred. "We were trying to distract Filch," he blurted suddenly, not meeting the headmaster's gaze. "We thought that this would... would help."

Dumbledore didn't even seem surprised. Instead, he glanced from Filch, who looked murderous, to Professor McGonagall, who was straight-backed and stiff. "Minerva... Argus..."

Both members of staff turned to look at him, Filch somewhat reluctantly.

Peter looked up too, still quivering, and Dumbeldore gave him a very small smile.

"I would like you to leave these boys to me. Minerva, if you could please fetch Mr Potter... I feel as though he has a role in this, too." For a moment, Dumbledore's eyes twinked merrily. Then he turned back to Peter, Remus and Sirius. "If you wouldn't mind, you three, I would like to have a brief word with you in my office. I believe you have some explaining to do and we might as well make ourselves comfortable. Please, follow me."

Feeling a bit bewildered at the lightness of Dumbledore's tone, Remus and Sirius moved to stand next to Peter, and the three of them followed Professor Dumbledore out of the classroom.

They came to a halt outside a large, stone gargoyle and Dumbledore held up his hand to indicate that the others should remain quiet. "Sugar quill."

Peter blinked in amazement, but before he had time to reflect on the headmaster's sanity, the stone gargoyle had leapt aside and realisation dawned. Oh, he thought, feeling slightly stupid. 'Sugar quill' must be the password to Dumbledore's office.

A flight of spiral steps had appeared in the spot where the gargoyle had been and Dumbledore led them up it, going around and around until all three boys felt dizzy...

At last, however, the stairs ended and they emerged in front of a door.

Professor Dumbledore politely let them inside.

The office was a small, circular room of astonishing beauty. A wide array of silver instruments stood on tables and the walls were covered in sleeping portraits.

Sirius turned to frown at one of the portraits above the headmaster's desk and Dumbledore, following his gaze, smiled softly.

"Ah," he said, his eyes twinkling again. "Yes, that is indeed your great-great-grandfather, Phineas Nigellus Black. I'm glad to see that you've spotted him."

The portrait in question, which featured a dark-haired wizard with a pointed beard, suddenly jerked awake. "I beg your pardon?" he said lazily, looking at Dumbledore with his dark, shrewd eyes. Then his glance fell on Sirius and his expression turned into one of disapproval. "Ah. It's you. The newly-sorted Gryffindor. The... how shall I put it?... disappointment to the family."

Sirius scowled and Dumbledore's smile hardened.

"Phineas!" he said sharply, making Peter and Remus jump.

Phineas sighed and leant against his frame, the faint crease in his forehead still prominent. "Oh, all right, Albus. But I'll stay, I think, and hear what the foolish boy has done. Knowing him, it can be nothing good."

"No one asked your opinion!" Sirius snapped, his expression one of mingled disgust and dislike.

Phineas Nigellus yawned widely. "No one asked your opinion, either," he said, his voice irritatingly smug. "You know, this is precisely why I detest small children. You see-"

"Phineas!" said Dumbledore, his eyes flashing. "Now, I am afraid, is not the time. Will you please do me the ultimate courtesy and leave my office. I'm sure Walburga and Orion would be delighted to see you in Grimmauld Place."

Looking confused, Peter and Remus exchanged glances.

"Phineas Nigellus Black," explained Dumbledore, noticing their bewilderment, "was a headmaster of Hogwarts many years ago. He is the great-great-grandfather of young Mr Black here..." Smiling, he indicated Sirius. "And he also has a portrait in Sirius' parents' house, which he frequently visits."

The three boys all turned their attention back to the portrait and Phineas sulkily slid out of sight.