Artemis didn't really care whether or not Merula would continue to be civil to her now that the new term was starting. She was more concerned with finding Tulip Karasu, the owner of the padlock she and Bill had found. That lock was the only thing keeping her out of the room her brother had used to research the Cursed Vaults during his own days at Hogwarts, and she was desperate to get inside.

Although she didn't know Tulip personally, she knew of her by name. Tulip was a Ravenclaw in her own year, had a reputation for being a troublemaker, and mainly kept herself to herself. Of course, when it came to their fellow students, Artemis' friends always knew more than she did.

"I like her. She's a right laugh," said Tonks, as the girls carried their Puffapods through the greenhouses in their first Herbology lesson of January. "She let me colour her hair last summer and she lent me a dungbomb after Filch confiscated all my Zonko's goodies."

"Sounds like you two are good friends," Artemis said.

"Not really. Tulip's a bit of enigma."

"What do you mean?"

"She doesn't give much away, or let people get close to her," Tonks shrugged. "But I'm working on it."

Artemis would have liked to know more, but their conversation was put to an abrupt end, as Tonks dropped all her Puffapods on the floor. The pods cracked opened, the seeds inside spilled across the ground and immediately began to bloom, much to the chagrin of Professor Sprout.

After lunch, the Hufflepuffs had Transfiguration with the Ravenclaws. Artemis made a note of where Tulip was sitting near the back of the classroom, easily recognisable by her hair, which Tonks had helped to colour a bright cherry red. As the bell rang at the end of the lesson, Artemis hung back near Tulip's desk.

"Excuse me, Tulip," she said, as she approached the girl. "I know we've never really spoken before, but I'm Artemis Hexley and -"

"I know who you are," Tulip, still seated at her desk, narrowed her almond-shaped eyes and gave Artemis a funny, mistrusting look. "What do you want, Artemis Hexley?"

"Well, it's an odd request," Artemis replied. "But the thing is, my brother Jacob was expelled a few years ago. And I've recently found out about a secret room he used to keep a lot of his stuff in. I wanted to see it, but the room is locked -"

"With my padlock, and you want the key," Tulip finished her sentence for her.

"Yes. Please."

"Ah," said Tulip, and she stood up. She was almost as short as Artemis herself. "The thing is, the padlock needs two keys to open it. I only have one of them."

"Who has the other one?"

"My accomplice."

"Who's your -"

"That's not exactly my secret to tell," Tulip folded her arms across her chest and gave Artemis another doubtful stare. "Besides, I hardly know you, Artemis Hexley. How do I know that I can trust you with my secrets?"

"You trust Tonks, don't you?" Artemis frowned. Tulip was silent. "I mean, you trusted her with your hair," Tulip still said nothing, but the corners of her mouth twitched slightly, "and Tonks trusts me. Also, that's my brother's room. If anyone should know what's inside it, it's me."

"You make a good point," Tulip uncrossed her arms and picked up her schoolbooks. "Very well, Artemis Hexley. The other key is with Merula Snyde. If she gives you her key, I'll give you mine."

Artemis decided to ask Merula about the key to her brother's room outright. Maybe Penny was right, and she would be less antagonistic after spending Christmas with Artemis and her friends. Unfortunately, this was not the case at all.

"You want me to give you a key to that secret room on the seventh floor?" Merula asked, glowering at Artemis over her cauldron. She looked around and lowered her voice to a low hiss. "Is that why you gave me a Christmas present, to butter me up?"

"No," Artemis shook her head. "I only found out about the key after the end of holidays."

But Merula was unconvinced.

"Whatever, Hexley," she snapped. "I knew you were only pretending to be nice because you wanted something. I wanted the Zonko's tricks so I went along with it. So the joke is on you."

"Merula, I honestly didn't -"

"Sod off. I'm not giving you anything," she flung her hand into the air. "Professor Snape, Hexley is distracting me. May I swap seats with Barnaby?"

Snape permitted Merula and Barnaby Lee to switch seats, and took five house points from Hufflepuff. Merula strode across the classroom, stopping only to whisper something to Barnaby as they crossed paths.

"That went well," Rowan muttered, watching her skulk away to sit with Ismelda Murk and Liz Tuttle. "Looks like Merula won't be joining us for Butterbeer at the next Hogsmeade trip."

"Penny will be disappointed," Artemis moved her ingredients closer to her as Barnaby Lee took the now empty seat next to her. "Barnaby, what did Merula just say to you?"

"When?"

"Just then, when she whispered to you."

"Oh, she asked me to spy on you two for her," Barnaby said, matter-of-factly. "And to tell me I'd have to cut up more bat spleens because she'd be taking the ones I'd just done. Actually, do you have any spare? It took me ages to dice that lot so precisely."

"Um, sure. Help yourself," Artemis frowned. She'd hardly ever spoken to Barnaby. He seemed a lot less tough and intimidating than she'd imagined him to be. "Barnaby, surely if you're spying on us, you shouldn't tell us that you're spying on us. I mean, it's not really spying if we know that you're doing it."

Barnaby looked at Artemis over his bat spleen, obviously perplexed. He was silent for a few moments.

"Could you maybe not tell Merula I told you? That I'm spying, I mean. She'll get really angry with me if she finds out I did it wrong. She already thinks I'm the most stupid boy in our year."

"Of course I won't tell her," said Artemis. "Barnaby, she didnt say that to you, did she?"

"Say what?"

"The thing about you being stupid."

"Oh, that," Barnaby returned to his bat spleens. He didn't seem in the least bit upset. "Yeah, she says it a few times a week, maybe."

"That's awful. Why do you put up with it?"

"I just do. I'd never really thought about why," Barnaby said, and he tilted his head to one side like a puppy. "But she did say if I helped her find the Cursed Vaults before you she'd make me the most powerful wizard at Hogwarts."

"And you believed that?" Rowan raised her eyebrows.

"Well," Barnaby looked confused again. "Why would she lie?"

"Because she wants you to make her look more powerful," Rowan replied. "Because you're muscly and good at duelling."

"You think I'm muscly?" Barnaby smiled and looked at his upper arms as if he'd never seen them before.

"What Rowan's saying is that Merula is more interested in getting ahead than she is in helping you become more powerful, or even in being your friend," Artemis said, her eyebrows furrowing even deeper. This was the strangest conversation she'd had in a while. Barnaby also frowned. Artemis couldn't tell whether he was upset or just thinking.

"I don't want to talk about this anymore," he said, scraping the diced bat spleens into the cauldron. "I'm just going to make my potion and carry on spying on you like I was told to. Okay?"

"Okay, Barnaby. You do that," Artemis said as she met Rowan's eye and shrugged.

Having had no luck getting the key from Merula, Artemis again approached Tulip Karasu.

"If Merula Snyde won't give you her key, there's not much point in me giving you mine. You need both to unlock the padlock," Tulip told her. "And anyway, I'm not really sure if I even want to give you my key, Artemis Hexley. I just don't know if I can trust you."

"You trusted Merula enough to give her a key."

"Merula Snyde and I were friends. We aren't anymore, but we were."

Artemis sighed. She hadn't anticipated that getting into her brother's room would be so difficult.

"Surely there's got to be something I can do to show you that you can trust me," she said to Tulip.

"Well, there is one thing," Tulip replied, after a moment's thought. "Professor Flitwick said the other day that a space has opened up in the Frog Choir. Merula was going to audition for a place at the start of the year with my toad, Dennis, but now that we're no longer friends, that's not going to happen."

"Right," Artemis nodded. "Sorry, but where are you going with this?"

"I can just tell that Dennis really wants to be in the choir. But he needs someone to sing and hold him, and I can't sing for toffee," Tulip smiled shyly at Artemis. "But maybe you could audition with him."

"Let me get this straight," Artemis said, completely baffled. Somehow, the conversation she had with Barnaby Lee in Potions that morning didn't seem quite so bizarre anymore. "You will give me the key to my brother's room if I sing in the Frog Choir, because your toad wants to join?"

Tulip flicked her bright red hair over her shoulder and looked away from Artemis.

"Don't worry if you think it's too weird for you," she said.

"I mean, it is weird. Very weird," replied Artemis. "But I'll do it if it gets me into that room. Although, don't you have to be able to sing to be in the Frog Choir?"

"Tonks said that you're quite a good singer."

Artemis laughed. Tonks was tone-deaf.

"That's a matter of opinion, I guess."

When Artemis asked Professor Flitwick about the Frog Choir auditions after her next Charms class, he was delighted to hear that she was planning on auditioning.

"We don't get very many students wanting to join," he explained, beaming. "Especially not this late in the year. And now there will be two of you trying out for the empty spot!"

"Who's the other person auditioning?" Artemis asked him, but she didn't need to. She knew the answer to her question before she'd even finished asking it.

"Miss Snyde. Merula Snyde."

Merula was not best pleased when she found out that Artemis was also auditioning.

"Ugh, isn't being famous Artemis Hexley the curse-breaker enough for you?" She sneered at her over her cauldron, having returned to her normal seat by their next Potions class. "Why do you have to try and one-up me at every turn?"

"I'm not trying to one-up you, Merula," Artemis said, stirring her potion. "But if you're so worried, why don't you give me the key to my brother's room? Do that, and I'll pull out of the auditions."

"I don't need you to pull out, Hexley. I know I'm a better singer than you could ever be."

But Artemis could tell she was anxious, and she noticed that Merula started to become even more foul-tempered than ever before. By the day before the audition, she had made cruel remarks that had reduced several of their classmates to tears, and poor Barnaby Lee looked even more bewildered than he normally did whenever Artemis passed him in the corridor with Merula and Ismelda.

"Don't you worry about her," Penny reassured Artemis, as the Hufflepuff girls walked past a glowering Merula on their way to the Great Hall after Defence Against the Dark Arts. "She just knows how wonderful you're going to be, that's all."

"I think wonderful is a pretty strong word, Penny. I mean, I'm not even sure I can sing that well!"

"What do you mean? Of course you can, silly!"

"When have you head me sing?"

"Lots of times," Penny beamed at her. "You know, sometimes when you're doing your homework or tidying your stuff in the dormitory. Do you not realise you're doing it?"

"Apparently not," Artemis said. Why had no one ever mentioned this to her before?

"Oh, how funny," giggled Penny. "Well, you have a lovely voice. It's unusual -"

"Great."

"- but it is very nice," Penny sighed, and turned her gaze to the Ravenclaw table. "You know, if you're nervous, maybe there's someone who could help."

"Who?"

"Chester Davies, he's a seventh year Ravenclaw prefect. He's in the Frog Choir and the school orchestra, too. He's a pianist."

"He's a what, now?"

"A pianist, Artemis," said Rowan, tutting and rolling her eyes as Tonks began to snigger loudly. "As in someone who plays the piano. Honestly..."

"Right," Artemis said, "and how is this" - she paused, making sure to pronounce the word carefully, so that Tonks wouldn't start laughing even harder than she already was - "pianist boy meant to help me with singing?"

"He might be able to practice with you beforehand," said Penny, and she immediately started to walk away. "I'll go and ask him now. Please could one of you save me a seat?"

Artemis wasn't sure what Penny had said to Chester Davies the pianist prefect in order to persuade him to help her, but he agreed to meet Artemis at lunchtime the next day. When she arrived in the disused classroom ready to meet him, he was already there, leaning against the only object in the room: a grand piano.

"You must be Artemis," he said, holding out his hand for Artemis to shake, which she did. He was tall, as tall as Bill, with high cheekbones, and dark hair and eyes, and a serious and slightly tired looking face. "I'm Chester. Penny Haywood said you're auditioning for the spare spot in the Frog Choir this evening."

"That's right," said Artemis, taking her hand back from him. It felt warmer than it had before.

"Great. Lots of the girls are in my year, so it will be good to have some younger female voices that will know the ropes after we all graduate in the summer," Chester sat at the piano, his hands gently resting on the keys. "Right, let's get to it. What song are you going to be singing?"

Artemis hadn't even thought about that.

"Um, I don't know. I assumed Professor Flitwick would just ask us to sing a song that the choir do."

"He will, and we can go over that if you like," Chester said, wearily. Artemis got the feeling that he was trying not to sigh or tut at her. "But he'll want to hear you sing something that you choose yourself, too," he paused, and started to rifle through a leather briefcase full of loose sheets of parchment and Muggle writing paper. "If you haven't had a chance to think about it, Celestina Warbeck would be a good shout. Flitwick loves her. Do you know 'You Charmed the Heart out of Me'?"

Chester's fingers pressed down on the keys, and the familiar melody started to play.

"I know it," said Artemis. "Not well, though."

"Well enough to sing it?" asked Chester, and Artemis nodded. "Go on then."

Artemis took a breath, and sang along to the piano, but she found it difficult to reach some of the higher notes, and she didn't like the way her voice sounded at all. Clearly, Chester didn't, either, as he stopped playing after only one verse.

"That was rubbish," said Artemis. "Maybe I should just let Merula have the spot after all."

"Actually," Chester replied, shaking his head, "I was going to suggest that we do something a bit different with it. Your voice is a lot lower than I was expecting."

"Is that bad?"

"No, we just need to change the key for you, that's all," he moved his hands down the piano keyboard, and played the same melody on a different set of keys. This time it sounded deeper, darker. "Can you sing it down here?"

"I can try."

Artemis did so, and suddenly, the song became easier to sing, and her voice sounded less strained, more forceful. She made her way through the song, making up the words when she didn't know what the actual lyrics were, and Chester didn't stop her once.

"That was better," she said, as the final piano note rang out.

"Much better," Chester nodded, but he was frowning. "Not sure it's the one for you, though. I think you need something you know really well. What music do you like to listen to?"

"Everything," said Artemis, feeling her own smile creeping across her face. "Muggle music, mainly."

"A girl of good taste. What kind of Muggle music?"

"Oh, all sorts."

"That really narrows things down."

"I don't know," Artemis frowned. "I just like the way that when you listen to a song, it can make you... feel something, I guess."

Chester pursed his lips, and began to sort through his case of loose sheets again. He picked another, placed it in front of him, and started to move his fingers across the keyboard again.

Artemis watched, transfixed, her eyes following his hands in the same way that Fergus' eyes might follow spots of light moving on the floor, as his fingertips danced on the keys, making each one sing out a different note. Forget spells, or potions, or flying; this was magic.

"Do you know this one?" asked Chester, his voice breaking the trance.

"Yes," said Artemis, suddenly realising that she hadn't been breathing. "But isn't that a boy's song?"

"Not if you're the one singing it. It's your song," Chester said, "so sing it how you want, and I'll work around you."

This time, when Artemis opened her mouth to sing, her voice was strong and unwavering, and when she had finished there were a few seconds of hushed silence from her, the piano, and the boy who had been playing it. The silence was broken by the sound of Chester's hands, clapping slowly, three times.

"Now," he whispered, "where did you learn to sing like that?"

"I didn't, really," said Artemis, and she leant on the piano, her elbow on the lid, her chin on her hand. "There was a Muggle who used to live on a boat behind my house. Reggie. He had all these big circle things called records, and he used to play them for me. Jacob had some records, too, and our Grandma, when I was little. She was a Muggle, too."

"Could she sing?"

"Yes, it was her job."

"That explains it," Chester nodded, and packed his sheets away. "You know, I was not expecting such a big voice to come out of someone so small."

"Yeah, well, I'm full of surprises."

After the afternoon's lessons had finished, Artemis returned to the classroom with the piano, ready for her Frog Choir audition. Considering it was only her and Merula who would be auditioning, the room was very full. Tulip Karasu was already there waiting, and the other Hufflepuff girls had decided to come along to support Artemis. Merula had her henchmen Ismelda and Barnaby with her, and at the piano sat Chester Davies.

"Just do what you did earlier and you'll be fine," he muttered to Artemis as she walked past him, and she nodded in response. Despite not really caring about being in the Frog Choir, her stomach was doing backflips. She took a deep breath, and willed herself to feel calm.

First, Professor Flitwick had Merula and Artemis sing a song from the choir's songbook together, then separately with Merula holding one of Flitwick's toads, and Artemis with Tulip's beloved Dennis. After that, the girls were asked to sing a song of their own choosing.

Merula went first, and sang the Celestina Warbeck song Artemis had tried earlier in the day. She had no trouble whatsoever hitting any of the high notes, and Artemis couldn't help but admire and envy her rival's crystal clear voice.

"She might be horrible," Rowan whispered, looking as impressed as Artemis felt, "but she really can sing."

Next it was Artemis' turn, and she stepped up to the piano.

"Ready?" Chester asked, his hands poised, ready to play.

Artemis nodded, and he started to play. The noise of the piano soothed whatever nerves Artemis had left, and as soon as she began to sing, she forgot all about Flitwick and Tulip, and the toads and the Slytherins, and even about Rowan. It was just her, her voice, and the piano.

When the music stopped, she remembered where she was. Chester looked at her and nodded curtly as he placed his sheets back inside his briefcase. Rowan was smiling proudly at her, Penny's hands were pressed to her mouth, and Tonks and Tulip were both smirking. Ismelda Murk was scowling, and Barnaby Lee's eyes were wide. Artemis could have sworn that they were full of tears. Merula's expression was unfathomable.

"Well," said Professor Flitwick, clapping his hands together, and looking delighted. "I think it's safe to say that both of you have given me a lot to think about. Perhaps if you come back after dinner, we can discuss which of you will take the place."

The students returned to the Great Hall, but when they got there, it was clear that Merula had gotten lost somewhere along the way.

"She went in the other direction when we got down to the ground floor, did you not notice?" Penny said, when Artemis pointed out Merula's absence. "It looked like she was headed for the viaduct courtyard. Poor thing, she looked rather upset."

Artemis sighed.

"I'll go and find her," she said, getting up from the table.

As Penny had said, Merula was sitting in the cloisters of the viaduct courtyard. She had clearly been casting the snowflake spell, as a small flurry of snow was floating down from a metre or so above her head, and she was watching the snow as it landed onto the ground in front of her, each drop leaving a wet mark on the stone as it melted. She looked as if she had been crying.

"Merula," Artemis said as she approached her. "Didn't you want any dinner? There's Bakewell tart."

"I'm not hungry."

"You know, you don't need to be worried about the audition. You have a really beautiful voice," Artemis sat down next to her. "And even if you don't get in, it is just a choir."

"Bog off, Hexley," Merula wiped her face with her sleeve. "You don't know anything about me."

"I know that this obviously means a lot to you."

"Yeah," Merula paused and sniffed. "My mum was in the Frog Choir when she was at Hogwarts. She was an amazing singer, and she taught me how to sing."

"She did a good job. You were brilliant back there."

Merula ignored Artemis' compliment, and carried on watching the snowflakes.

"She used to sing that song to me," she said quietly, still not looking at Artemis, "the one you sang for your audition. She used to say it was my song, just for me."

"But it's a Muggle song."

"I know that now, obviously."

Merula scowled and looked away. Artemis sighed.

"So that's why you wanted to join the choir," she said. "To make your mum proud."

"Kind of. And to just feel, I don't know, closer to her somehow," Merula rolled her eyes. "I wouldn't expect you to understand."

"The thing is, I do understand," said Artemis. "It's exactly how I feel about my brother. That's why getting into his room is so important to me."

Merula looked at her with narrowed eyes.

"Again, being kind just to get something you want from me," she sniffed. "Some Hufflepuff you are."

"Merula, no, I -"

But Merula had already walked away.

When Artemis returned to the piano room, Merula was already there, as were Professor Flitwick, Tulip, and Dennis the toad. Flitwick cleared his throat.

"Um, Professor," Artemis said, before he could say anything. "I'm really sorry. I know I said I wanted to audition for the choir, but I've changed my mind."

Professor Flitwick looked surprised.

"You've changed your mind?"

"Yeah. The thing is, Merula is a better singer than me, and it means much more to her. So I think you should give the empty spot to her."

"Are you sure, Miss Hexley?"

"I'm sure. I'm happy to let Merula have the spot," Artemis turned to Merula, who looked even more surprised than Flitwick. "On one condition, that is."

Merula groaned loudly.

"Forget it, Hexley. I'm not giving you that key."

"I wasn't going to ask you for the key," Artemis shook her head. "I just want you to promise that you'll sing with Tulip's toad Dennis. Because that means a lot to her."

Merula rolled her eyes, but she nodded her head.

"Well, that settles it, then," Professor Flitwick squeaked. "Congratulations, Miss Snyde."

As they left the classroom, Tulip turned to Artemis.

"That was really kind," she said. "Maybe Tonks is right to trust you, after all. I'll give you my key. And I'll help you get the other key off Merula."

"Ugh, if having the bloody key means that much to you, Hexley, you can have it," a voice said from behind them. Merula was leaning against the wall, watching the two of them talking. She reached into her pocket and pulled out a key. "I've already taken what I wanted from your brother's stupid room, anyway."

"Thank you, Merula," Artemis smiled. "And congratulations for getting into the choir."

"Whatever. I knew you'd pull out of the audition as soon as I told you that stuff I made up about my mum. You're really gullible, you know," she laughed and threw the key to Artemis, who caught it one-handed. "Means you'd better watch yourself. Especially with that Karasu. She'll stab you in the back like she did me. Just you wait."

Delighted, Artemis went back to the dormitory, expecting the other girls to ask her about the audition, but instead they we're flustered about something else entirely.

"What is it? What's wrong?"

"Artemis, when we came back from dinner, we found a letter on your bed," Rowan said. "We don't know how it got there. There wasn't an owl here or anything."

"What?" Artemis went over to her bed, where an envelope lay next to a sleeping Fergus. She opened the envelope, and pulled out a sheet of folded parchment, and read its message.

Artemis, I have reason to believe that you are in danger. Your involvement with the Cursed Vaults has drawn the attention of a group that are not to be trifled with. Be careful, but remain courageous. I will assist you where I can. I hope that the next time we correspond, the circumstances will be less mysterious. Yours sincerely, A Friend.