Three days later, Leo had an idea of how it must feel to be imprisoned. It was driving him mad. With no access to the library, he couldn't research any more spells, or follow up on any of the Chamber leads. With no access to the grounds, there could be no more Snow Leopards meetings. With the six o'clock curfew in place, he couldn't go to the Room of Requirement to check on Marisa's potions, some of which must have been completely spoiled by now.

But the worst thing of all was that there was no Marisa.

The attack on her had affected the rest of the group greatly. There was an air of paranoia around them. None of them had been afraid before, because they were Slytherins, they were safe. But now they knew the monster wouldn't hesitate to harm someone from Salazar's own house.

They played Exploding Snap obsessively, because none of them had anything better to do. They were sick to death of the game before long, but there was a determination to take advantage of Marisa's absence and overtake her on the leaderboard. With the formidable advantage she'd built up, this was no easy feat, particularly when every time one of them got close the pack exploded and they lost a hundred points.

Leo spent as much time as he could focusing on his homework. He wrote twice as much as he needed to for most of the essays, even to the point when Professor McGonagall told him he didn't need to write that much.

"I can't stand this any longer," he said finally on Tuesday evening. There were still three days until Double Potions. "We have to do something."

"No," said Theo, "you have to do something. I don't have to do anything, and nor does Daphne or Tracey."

"Fine," said Leo. "If you don't care about Marisa, then don't do anything. I have to do something. Does anyone want to help?"

"I'll help you," said Tracey. "As long as it won't get us in trouble."

Leo suspected that Tracey had ulterior motives for wanting to help him, but right now he really couldn't be bothered to deal with that kind of thing. "Well, the only plans I have all kind of involve sneaking out, so… yeah, it will get us in trouble. If we get caught. Which I don't plan to do, but…"

"You can't sneak out! You'd probably get expelled!" said Daphne, aghast.

"Are you seriously considering that? Please tell me you're joking," Theo added.

In that moment he missed Marisa more than ever. She wouldn't have been horrified and reluctant and refusing to help. She would have agreed and got to work on a plan for how to do it straight away.

"Look, we all miss her," Theo said hesitantly. "We all like her, and we all want her back. But she's going to come back as soon as the Mandrakes are ready. If sneaking out meant the difference between saving her and not… I'd do it, but now? What good is it going to do?"

"It could solve the mystery," said Leo, coldly furious, "and prevent more people from being attacked."

"What do we care?" asked Theo. "We're all safe. Slytherin's monster would never come near any of us."

"And that's all you care about?" asked Leo, instinctively getting to his feet. "You don't care about all the Muggle-borns in Gryffindor and Ravenclaw and Hufflepuff who are afraid for their lives? You don't care if one of them dies? They could close Hogwarts if there's another attack, Theo! Don't you at least care about that?"

"Of course – it's not – do you really think -?"

"No," said Leo furiously, not stopping for one second to think about what he was saying: all his anger and frustration from these last ten days was boiling over. "You don't care, do you? You don't care about Marisa, you don't care about Hogwarts, you don't care about anyone other than yourself!"

Theo had reached breaking point. He stood up, too, and replied, "Don't lie! I do care! I'm not the one who has a problem, it's you! You care too much! It's always Marisa this, Marisa that, I don't see what's so special about that girl, she's just a – " He fell silent at the look on Leo's face.

Leo knew, as everyone did, what the next word would have been: Mudblood. "Just a what?" he asked, voice trembling with anger, one hand reaching for his wand, the other clenched into a fist.

Theo didn't usually have the tact to back down in these situations, but this was different. He had never seen Leo this angry before.

"Just a Mudblood." It was not Theo who had spoken, but Draco, who had been drawn over by the raised voices.

"Marisa," said Leo, completely forgetting every resolution he had ever made about not showing Draco his true opinions, "is not just a Mudblood. She is so much more than that."

"Oh, really?" asked Draco sarcastically. "I hadn't noticed."

"Isn't it obvious?" spat Leo. "She's better than you at Quidditch – have you even seen her on a broom? Even I can tell she's a born flyer! – and her grades are better than yours and she's a thousand times smarter than you!"

Draco's mouth flew open in shock and outrage at this, but he was stopped from saying anything by the look in Leo's eyes, which was genuinely terrifying. It made all the Slytherins flinch from him and avert their eyes from his terrible gaze.

There was a long moment of silence, broken only by a muffled sob from someone. Leo was too furious to care who. Eventually he turned and strode upstairs to his dormitory without a word to anyone.