Despite the cold weather outside it was rather uncomfortably hot inside the Potion's classroom. This was due to the boiling bubbling cauldrons that each pair of students were currently working around. George had been paired with Lee as most teachers, Snape included, had long worked out that pairing George and Fred together was just asking for trouble. Instead, Fred had been paired with Angelina.

"Will you pay attention?" snapped Angelina, who had been busy counting out a number of ingredients before dropping them into the golden liquid contain in the cauldron. Fred was slowly stirring it with a large wooden spoon. "Not too fast. Remember, you're supposed to be making a circle every seven seconds."

"I'm sure it won't make much of a difference," muttered Fred, who kept looking over at his brother and Lee.

"Five times. Five times, I've been paired with you or your brother during this year and do you know how many times something has exploded on me?"

"Once?" ventured Fred.

"Five times. So pay attention because there won't be a sixth. Not today," said Angelina, putting in the last of the ingredients. She turned to look back at the book. "Right, what's next?"

George looked over at Snape who was busy examining one of the other group's work. Lee grabbed hold of the wooden spoon and started stirring his cauldron, he nodded at his friend who in turn nodded at his brother. Fred, making sure Angelina was too preoccupied measuring out the next ingredient, carefully took out a vial from his pocket and emptied half the contents into his mixture.

"And this should be it," said Angelina, dumping a jar of blue powder into the cauldron. "Careful, Fred. You're stirring too fast. I said, you're stirring too fast. Slow down. Fred! You're…"

Angelina's next words went unheard as a loud cracking sound deafened everyone in the room, this was swiftly followed by a bright flash.

"Arghh!" everyone tried to cover their eyes.

"What was that?" someone shouted.

"Calm down this instant," bellowed Snape as he blinked to try and clear his vision.

It took a few more minutes before order was restored to the classroom. Only Fred and Lee noticed George shuffling back into position behind his table.

"Did you get it?" whispered Lee.

"Couldn't find it," muttered George. "We need another distraction."

"This is a very simple potion," said Snape, who had now descended on Fred and Angelina's table. "Even the most foolish imbecile should be able to get it right. You just have to follow the instructions."

"We did. We followed the instructions," said Angelina, her face was covered in soot and her hair was smoking slightly.

"Obviously not," said Snape. "Two points from Gryffindor. Pour it out. Start again."

"I told you, you were stirring it too fast," said Angelina as she and Fred carefully lifted the cauldron to the stone basin and poured out the contents that had now gone a rather sickly green and lumpy consistency.

"Maybe you got the measurements wrong," countered Fred. He looked over his shoulder and raised his eyebrows. George shook his head and twirled his fingers around each other.

What? - Fred mouthed to his brother.

Again, do it again, - replied George.

"This time I'll stir and you measure out all the ingredients," said Angelina.

"Fine," said Fred. He looked down at the table, then over at the book, then back at the girl. "Er…"

"See those?" said Angelina, pointing at some green roots. "Five of them, cut up long ways. Then two cups of that powder. And finally pierce one of those purple things and put everything in in that order."

"That's it?"

"That's the first part. Weren't you even paying attention earlier?" said Angelina, frustrated.

"My job was stirring," complained Fred.

"And you weren't even doing that right."

"Fine, here we go."

"Wait, it's not even boiling yet. Do you want it to explode?"

"Well…"

"No, the answer is no. Do you want it to explode? No, I don't want it to explode. Because wanting it to explode would be mental. I'm not mental and you're not mental, so we don't want it to explode." Angelina wiped her hand across her forehead and looked around the room. Everyone had stopped working and was staring at her. She waved a hand at Fred. "Just get on with it will you?"

"Yes, boss," said Fred, giving her a salute before starting to cut up the roots.

Once the water was boiling Fred, under close supervision from Angelina, began dropping the ingredients into the cauldron in the correct order.

"One, two, three, four, five, six, seven," muttered Angelina under her breath as she slowly stirred the contents.

Eventually they reached a point where the liquid turned the required gold colour and was ready for the next stage. Fred looked over at his brother who nodded encouragement.

"Right, measure out seven ounces of Berbowa extract," ordered Angelina.

"Er…"

"The blue stuff there," said Angelina, pointing.

"Oh right," said Fred picking it up. He carefully poured out the correct amount and turned back to his cauldron. He pointed to two students behind Angelina. "Is it going to turn that colour?"

As Angelina turned to look at the other table, Fred poured the Berbowa extract, along with the rest of the vial from his pocket, into the cauldron.

"Hopefully. If we've done everything right," said Angelina, turning back and continuing to stir. Fred closed his eyes.

CRACK!

"Not again," shouted a voice.

"My foot, someone trod on my foot," shouted another.

Once again there were a few minutes of disruption as people's vision and hearing gradually returned. By the time Angelina was able to see again Snape was already standing next to her.

"I don't know why it isn't working. I'm following everything we're supposed to," moaned Angelina in a defeated tone.

"Maybe Mr Weasley has an explanation," said Snape, turning to look at the boy.

"Haven't a clue sir. Maybe the book is wrong?" he tried.

"The book?" said Snape, raising an eyebrow. "The Potion's book? The Potion's book that has been assigned to third year classes for the last seventy years… is wrong?"

"It's possible," said Fred.

"Or maybe it could be because you decided to add an extra ingredient into the mixture. Turn out your pockets Mr Weasley," said Snape, staring at the boy with unblinking eyes.

"My pockets?" said Fred, trying to sound innocent. "No problem."

He pulled each of his trouser pockets so that the insides hung out, before doing the same with the side pockets on his robes. As he had reached into the pocket that contained the vial he carefully adjusted his hand and palmed the bottle before pushing it up his shirt sleeve as quickly as he dared. It was a useful skill that he and his brother had developed out of necessity over the years.

"It appears I may have been mistake," said Snape coolly. He held out a hand. "Please accept my apologies."

"Oh… er… of course," said Fred, momentarily taken aback, as was pretty much the whole class. He reach out his hand and shook Snape's. As they were shaking hands, Snape gripped firmly and pulled the boy closer, he then used his spare hand to push Fred's robe and shirt sleeve back. The vial dropped out and bounced off his shoe before rolling noisily across the floor. Snape stopped its journey with his foot.

"A Thunder and Lightning Potion if I'm not mistaken. A simple but relatively pointless solution," said Snape, smelling from the vial. He looked at Fred. "Any thoughts as to how this found its way up your sleeve?"

"Er… magic?" tried Fred.

"Is that the best you can come up with?"

"At the moment. I could come up with something better if you gave me some time."

"How much time?"

"Four or five years might do it."

"Very amusing," said Snape with a tight-lipped expressionless face. "Now we have the 'how', we have the 'who', all that remains is the 'why'? Care to venture any thoughts Mr Weasley?"

"Not really," said Fred, shaking his head.

"Actually I was asking the other Mr Weasley?" said Snape, looking up at George. All eyes were now turned to the other twin.

"Me sir?"

"Did you find what you needed in my private stores? It must have been very important to require two trips."

"Ah… well…" Before he could answer the school bell signalled the end of class.

"You two will stay behind and clean out everyone's cauldron while I check the contents of my supply room," said Snape, pointing at Fred and George in turn. "Everyone else dismissed."

"I am never being your partner again," whispered Angelina as she grabbed her bag. "Seven times now. Seven!"

"Bad luck guys," said Lee compassionately.

"Don't worry about it," said Fred, slapping him on the shoulder.

As the rest of the class filtered out, Fred and George removed their robes and pulled up their sleeves of their shirts and began taking each cauldron to the basin to empty. Most of them were okay to clean but the odd few, most notably belonging to those students who generally received poor Potion's marks, smelled so badly that the boys pulled their shirts up over their noses to try and block some of the stink from invading their nostrils. It was not very effective.

"Sir?" said Fred, once they had cleaned out all of the potions. "We've finished."

"Then wait until I have finished checking my supplies," said Snape's voice from the next room.

"Did you get it?" whispered Fred.

"Couldn't find any?" answered George.

"I said 'wait' not 'talk'," said Snape.

They patiently waited as the minutes ticked passed. One minute. Five. Ten. Twenty. In the end it was nearly a full hour before Snape returned to the classroom.

"It appears there is nothing missing," said Snape slowly. "What exactly were you looking for?"

"Lapburg Root," said George quickly.

"Lapburg Root is on the second shelf on the left and is marked very clearly," said Snape. "Try again."

"We were looking for a unicorn horn," said George, reluctantly.

"Why?"

"We were trying out some potions for ourselves," said Fred.

"Yeah, because we really love the subject," said George, trying to appear earnest.

"Very well. Detention for both of you, and five points from Gryffindor for disrupting my class, and a further five points for continuing to lie."

"But we're not lying."

"Forgive me if I am not convinced. If any further ingredients go missing you two will be the first to be interrogated. And rest assured the experience will not be pleasant. Now leave."

"Well that was close," said Fred, once they were on the other side of the door.

"What do you mean 'close'? He caught us, you can't get much closer than that."

"You really didn't find any?"

"Nah, the drawer was empty. Probably all been used up over the year. I wonder if he's getting any more in," said George.

"You want to go back and ask him?"

"Maybe not," conceded George.

The two boys made their way up from the dungeons where the Potion's classroom was located to the main hall. They were just about to start climbing the staircases towards Gryffindor Tower when a rather worried looking Lee met them coming down the other way.

"Alright Lee?" asked Fred.

"No," said Lee, shaking his head. "I got a message that McGonagall wants to see us in her office."

"Us? All three of us?" said George.

"Yep."

"That can't be good," said Fred. The three boys made their way up to the first floor of the tower where McGonagall's office was located. Along the way they tried to work out what she could possibly want with all three of them, they kept coming back to the most obvious answer.

"We might not be in trouble," said Lee, hopefully.

"True, but let's face it, we're in trouble. The only thing is I have absolutely no idea what we've done," said George.

"You do remember our Potion's class that we just had?" said Lee.

"Yes, but only Fred and I got in trouble for that. Individually we've done things that would get us into trouble. But not all three of us," explained George.

"Yeah, you're like our safety net, if you're in trouble as well it narrows down the list of what we could have done," said Fred, patting Lee on the shoulder. They had reached the door to McGonagall's office. No one moved. "Should we knock?"

"Probably," admitted Lee.

"Well go on then," said Fred, nodding encouragement.

"Why do I have to knock? You knock."

"I don't want to knock. George, you do it."

"I'm not doing it."

"How about we all do it at the same time?" said Lee.

"Seems fair. On three?" said George, looking at the other two for confirmation. "Okay. One, two, three."

No one moved.

"You didn't knock," complained George.

"You didn't either."

"Well I wouldn't have to if one of you had done it."

"If you've quite finished with your dilly-dallying, you can come in," called McGonagall's voice from inside the room.

"Is she talking to us?" whispered Fred.

"For goodness sake," said Lee, shaking his head. He pushed open the door and made his way inside.

McGonagall's office was a large room decorated with a number of tartan plaid wall hangings. A roaring fire blasted heat into the room while on the mantelpiece there were several black and white photos of various wizards and witches.. McGonagall was sat behind her desk looking rather stern while in front of her were two seats which were currently occupied, however the figures had their back's to the door.

"You wanted to see us?" said Fred. At the sound of his voice the two people in the chairs turned around. One was immediately recognisable. "Alright Miro, what are you doing here?"

"Er… well," said Miro, looking a bit embarrassed. He looked over to his companion who seemed familiar to the twins.

"Did you three send Mr Franca here a letter?" asked McGonagall, her lips in a tight thin line.

"A letter?" said George, pretending to frown.

"Yes, a letter. In which you say, and I quote 'there's a Kosa in the Dark Forest that tried to kill us, any chance of some help?'," said McGonagall, reading from the letter in question. "Upon receiving this letter, Mr Franca showed it to his trainer Mr Lexington…"

"That's where I know you from," said George, who had spent the last couple of minutes trying to guess the identity of the man. "You attacked us in Diagon Alley, well not us, Miro, but it's still the same thing."

"And that's why I'm here," said Mr Lexington. "A Kosa is serious business."

"We don't even know if there is one," said McGonagall sternly.

"But these boys saw one," said Mr Lexington, he jabbed a finger down on the letter. "It says so right here."

"Yes, but these particular boys…" McGonagall tried to think of a diplomatic way of voicing her thoughts, "well let's just say there's a credibility factor that has to be taken into account."

"What does that mean?" said Fred.

"She's calling you liars boy," said Mr Lexington.

"I wouldn't have put it quite like that," said McGonagall, quickly. She leaned forward in her chair. "Now, think about this carefully. Are you absolutely sure that you are telling the truth? That you went into the Dark Forest, unaccompanied, at night, despite it being expressly forbidden and that you encountered a magical creature that the Ministry of Magic itself has classified as extinct? Is that what you are saying?"

"Actually, no. We definitely weren't out of Gryffindor House after hours and we certainly would never even dream of going into the Dark Forest. Would we Fred?" said George

"Of course not George. Wouldn't dream of it. I've never once been in that forest and I don't have any plans to either," added Fred. "Right Lee?"

"Er… right," said Lee, a little bit confused.

"Then why did you write this letter?" asked McGonagall.

"The letter? Right, well the reason I wrote that…" said Lee, trying to think of an answer.

"It's obvious isn't it?" said George, shaking his head.

"It is?" said McGonagall.

"Yep," nodded George.

"And are you going to furnish us with this obvious explanation or are we to guess?" said McGonagall, leaning back on her chair.

"Oh right. It's for… erm…"

"It's for school," said Fred quickly, once it became his brother was struggling for an answer.

"For school?" said McGonagall sceptically.

"Defence Against the Dark Arts," said Lee.

"Yes," said Fred, pointing at his friend. "See, Professor Quirrell set us an essay about dangerous creatures."

"And it could be about anything so Lee wanted to write about the Kosa," said George.

"I picked Werewolves, I've always been a dog person," said Fred. "Well they're wolves but they're like cousins to dogs aren't they?"

"What has all this got to do with writing to Mr Franca?" said McGonagall tersely.

"Ah… well…" said Lee, he looked over at his friends for some help.

"It's because he was cheating," said Fred.

"No, I'm sure it wasn't that," said Lee, shaking his head slightly.

"Yeah, there aren't many good books in the library on the Kosa," said George, picking up the lie and running with it, "so he figured if he wrote to Miro, then he might know a bit about them. What with being an Auror and everything."

"See?" said McGonagall, turning to look at Mr Lexington. "Nothing but fanciful thoughts from an over-imaginative child. I am sorry you wasted a trip up here."

"A trip back to Hogwarts is never wasted Professor McGonagall," said Mr Lexington, smiling kindly. "Since I am up here I don't suppose I could get a tour of the castle. It's been years since I was back and I'd like to see the old place again, if you don't mind."

"Of course not," said McGonagall, rising from her chair.

"Miro, why don't you catch up with your old chums?" said Mr Lexington. "I'll meet you in the main hall in an hour. Off you go."

"Oh, yes Mr Lexington," said Miro, nodding to the man. He stood up and motioned to the three boys to leave the room with him.

"Mr Jordan, I shall talk to you later regarding how each student must do their own homework," said McGonagall as the boys were leaving.

"Yes Professor," said Lee. Outside he turned to the twins. "Thanks for that. I'll probably be put in detention now."

"That's better than being punished for being out of Gryffindor House late at night and for entering the Forbidden Forest. Probably get expelled for that," said George.

"I didn't do either of those things," complained Lee.

"So what actually happen?" asked Miro.

"Wait. You believe us?" said Fred.

"Let's move away from here," said Miro, waving them down the corridor. After a few steps he continued talking, "to be honest when I first got the letter I thought you were just trying to wind me up, but then Mr Lexington saw it and all hell broke loose. He petitioned to have a whole squad of Aurors come up to the school and comb through the forest."

"Well, why didn't they?" asked Lee.

"Because the Ministry didn't believe him. There's a reason there aren't many old Aurors," explained Miro as the three boys walked. "It's a dangerous job, most are killed while on duty, those that don't start getting a bit paranoid. They start seeing danger when there isn't any."

"So you're saying he's two wings short of a Pegasus?" said Fred.

"Two barn owls short of a post office?" added George.

"Two… er… carrots short of a… casserole?" said Lee, looking at his friends uncertainly.

"That works," nodded George.

"What?" asked Miro frowning.

"He's nuttier than… erm… something that contains a large amount of nuts," said Fred.

"A squirrel's pantry?" said George.

"Yes, that would be it," said Fred, pointing at his brother. "Nuttier than a squirrel's pantry."

"He's not crazy, just… eccentric," said Miro, finally settling on a suitable word.

"Yeah, eccentric like a cuckoo," said George, twirling his finger in a circle around his ear.

"Look. Do you know who killed the last Kosa?" asked Miro. The three boys just shrugged. "Mr Lexington did. It was years ago and the Ministry gave him this medal and had a big ceremony and everything. They declared that the Kosa were extinct, but Mr Lexington never believed it. He always thought there were more of them. He has a whole file on weird unexplained disappearances or murders that he thinks are down to one or more of them. So when he saw my letter, that was all the encouragement he needed."

"So it's just you two then?" said Fred.

"Yeah, the Ministry won't help," said Miro. "In fact if they realised that's why we're up here Mr Lexington would be demoted or fired from the Aurors."

"What about you?" asked Lee.

"Our cover is that I'm being brought up here for training. The Dark Forest has a whole bunch of dangerous creatures so it's pretty believable. Mr Lexington said if anyone found out what we were really doing up here then he'll just say he didn't tell me anything and that I thought it was really just training. Although let's face it fighting a Kosa would be a pretty intensive bit of training."

"Great," said George, "so what can we do to help?"

"You can stay out of the way for a start," said Miro. He held his hand up before anyone could complain. "Look, you aren't trained, you don't know nearly enough spells and you'll only get in the way. Even I shouldn't be up here, this is a job for actual Aurors but Mr Lexington needed back-up and there wasn't anyone else."

"So you just expect us to hide in the castle?" scoffed Fred.

"That's exactly what we expect," said Miro. "The Dark Forest is dangerous enough in the first place."

"What if he comes to the castle? What then?" asked George.

"That's easy," said Fred. "We go hide in the Forest."

"He won't come into the castle, it's too dangerous for him," said Miro, shaking his head. He reached into his pocket. "But if he does, and that's a big if, you should have these on you."

"Nice one," said Fred, taking one of the two unicorn horns that the trainee-Auror was holding.

"We've been trying everywhere to get one of these," said George, taking the other horn.

"Hey, what about me?" complained Lee.

"He's not after you," explained Miro. "Besides these were expensive so we could only requisition four without raising suspicion, and we need the other two. I'll expect them back."

"So what's the plan?" said Fred, swishing the horn around like a wand.

"We've booked a couple of rooms at the Three Broomsticks. We'll stay there at night and hunt the woods during the day. Hopefully we'll find him in the next week or so. That's the longest we can stay away without questions being asked."

"What if you don't find him in that time?"

"I don't know," said Miro. "But it won't be good. We'll meet up with Mr Lexington later. He'll want to hear everything about your encounter with the Kosa."