Professor McGonagall made a special announcement at dinner that evening.

"By now, you have all heard about the attack on Molly Hooper." The headmistress, always a very serious woman, had never looked so grim. "I will be frank. Miss Hooper is alive, but her condition is very serious—far more serious than that of the two students who were poisoned last term. It appears that, rather than being exposed to a small amount of Sanguinoculus through her skin, as the others were, she was forced to actually swallow some."

John felt like he might be sick. He looked around the Great Hall, wondering which of his classmates was capable of such evil. If the monster was present, then she was a remarkable actress; the faces surrounding him all looked as disgusted and terrified as he felt.

"I tell you this, not to frighten you, but to impress upon you the severity of the situation," McGonagall continued. "These attacks are getting more violent. I fear it is only a matter of time before someone is killed. If you know anything—if you have even the faintest idea who might be responsible—tell a professor immediately."

John thought about McGonagall's words all night. Should he go to a professor with what he knew? It seemed pointless, considering Ron and Harry already knew all about Irene Adler. They didn't know about the watch, but how would John explain that? Excuse me, professor. I thought you should know that my friend Sherlock thinks the poisoner left a secret message in the form of a wristwatch…

Deep down, John knew he wouldn't go to a professor regardless. The reason was simple: it was all his fault. He had known that sending Molly in to look for evidence could be dangerous, but he had said nothing. As the oldest of the group, he should have been more responsible. This was his mess, and he would clean it up himself.

Well, not entirely by himself.

O0O0O

"Irene must have had an accomplice," he announced at breakfast.

He had been up all night thinking about it. It was too big a coincidence, the real culprit being in the Slytherin common room when Molly just happened to be there and Irene just happened to have an airtight alibi. Irene must have guessed what they were planning when Ron and Harry asked to speak with her and sent someone to keep an eye on her stash.

"Maybe it was a two-person job all along," John continued. "This other person did the poisoning, Irene sold the antidote, and then they split the profits."

"A sound theory," Sherlock said without looking up.

He was reading what appeared to be an astronomy book. This was odd, considering that Sherlock had said just the other day that astronomy was useless, but John was too engrossed in his own thoughts to ask about it. He only felt annoyance at not having the other boy's full attention.

"We should start by investigating Irene's friends," he said. "She's probably working with another Slytherin girl—maybe that blonde who always follows her around."

Sherlock grunted vaguely.

"You know, Molly is lying in a coma right now because of you," John snapped. "You could at least pretend to care."

Sherlock finally looked at him.

"You think I don't care?" he asked quietly.

"It certainly doesn't look like it."

Sherlock held up his book. "If I didn't care, would I be wasting my time reading up on bloody astronomy?"

John opened his mouth, then closed it again.

"Er…are you saying astronomy is going to help you catch Molly's attacker?" he ventured at last.

"It might."

Sherlock pulled a wristwatch out of his pocket and set it on the table. John recognized it immediately as the one Molly had been wearing.

"You stole that?" he asked incredulously.

"Of course. How else was I going to examine it properly?"

From behind them came a derisive snort. Both boys turned to see Sally Donovan glaring at Sherlock.

"You know, I hear serial killers often steal personal items from their victims," she said. "Things like watches and jewelry. They keep them as trophies."

John was outraged on his friend's behalf. "You're not still on about Sherlock being behind all this!" he said. "Look, the poisoner is a girl. She has to be."

"Oh, yeah? What makes you say that?"

John explained about boys not being able to get into the girls' dormitories. It was extremely satisfying, being able to prove Donovan wrong. However, to his dismay, she only shrugged.

"So he couldn't get up the stairs," she said. "Maybe he nicked a school broom and flew in through the window."

John and Sherlock looked at each other.

"That's…not entirely implausible," said Sherlock. He looked as taken aback as John felt.

"Is that a confession?" Donovan asked.

"No, it bloody well isn't!" John answered. "Don't you have anything better to do than harass Sherlock?"

Donovan departed with one last suspicious look.

"You didn't even try to defend yourself," said John. "Do you want people going around saying you're the poisoner?"

"It matters very little," Sherlock said calmly. "Besides, the best way to clear my name is to catch the real culprit. So let's get back to the case, shall we?"

John sighed. "Okay," he said. "Explain to me what astronomy has to do with this watch."

"That would be obvious if you actually bothered to take a look at it."

Grumbling, John picked up the watch. It was a large, old-fashioned affair, more like his dad's watch than something an eleven-year-old girl would wear. It was also clearly magical; in addition to telling the time, the face was covered in tiny pictures of the crescent moon, the nine planets circling the sun, and a storm cloud, which he guessed represented the weather.

"Okay, so it tells you what the moon and the planets are doing. But the time is wrong—it's stopped on twelve o'clock." John glanced up at the ceiling of the Great Hall, which was currently a beautiful, bright blue. "And it's wrong about the weather, too, so maybe everything is stuck on the wrong thing. Do you think it's some sort of code?"

"Obviously," said Sherlock. John was getting rather tired of that word. "The question is, how do we crack it?"

"Maybe we should focus on finding the accomplice instead," John suggested.

"That's what I'm doing," said Sherlock, in the tone of voice one would use to explain something to a five-year-old. "I'm going to find the accomplice by breaking the code."

"Wouldn't it be easier to just interrogate Irene's friends?"

"Easier, yes. More effective? Unlikely."

It was the first serious argument in the history of their friendship. Sherlock was convinced the watch was their best bet, but John couldn't see how decoding secret messages was faster than simply talking to people. In the end, they came to an agreement: John would investigate Irene's friends while Sherlock focused on the poisoner's clue.

Even knowing Sherlock's miraculous talents, John felt like he had a decent chance of solving the mystery first. By evening, however, his confidence had diminished.

He started by investigating the other sixth year Slytherin girls, figuring they would know Irene the best, but it turned out that they were all in Potions when Molly was attacked.

"Was anyone missing from class that day, aside from Irene?" he asked again and again. "Did anyone leave class for a few minutes? Maybe to use the loo?"

"No one."

"Not that I remember."

"I didn't notice."

"Why should I tell you?"

Why did I even bother? John thought bitterly. They were Slytherins, and he was a Muggle-born Hufflepuff. Even if one of them had seen something, they weren't going to tell the likes of him.

At dinner that night, Henry offered to ask around for him. "I hate to admit it, but they might be more open with me—you know, me being pureblood and all."

John politely turned him down. He had already let one friend get hurt playing detective for him and Sherlock; he wasn't going to make that mistake again.

He was trying to decide what to do next when a slip of parchment land next to his plate. He looked up just in time to see an owl swoop out the nearest window.

"That's weird," said Mike. "I've never seen an owl deliver post at dinner."

John unfolded the parchment and read:

John,

If it's not too much trouble, could you stop by the Transfiguration classroom after dinner? Ron and I would like to ask you a few questions.

Harry P.

"Bloody hell!" said Henry, reading over his shoulder. "You weren't kidding. You really do know Harry Potter!"

"I wonder why he wants to see me and not Sherlock," John wondered aloud.

"He probably figures you're more likely to cooperate," said Mike.

John thought that was a very sound theory.

Ron on Harry were waiting for him when he reached the Transfiguration room. After the usual pleasantries, Harry launched right into the interview.

"The girl who was attacked last, Molly Hooper—she's in Hufflepuff."

John had a feeling he knew where this was going.

"Er, yes, I know," he said. "She's a friend."

"Is she?" Harry raised his eyebrows. "Then maybe you can help us out. We've been trying to figure out what she was doing in the Slytherin common room."

"She was looking for Irene Adler's stash of potions."

He couldn't see any point in lying. Harry must have already suspected the truth, otherwise he wouldn't have asked John in the first place. Besides, he hadn't technically done anything wrong…at least, he didn't think so.

"I see," said Harry. The famous Auror's expression was unreadable. "Now, what made her do such a thing?"

"It was Sherlock's idea. But if you ask him, he'll say it was your idea, sir."

"My idea?" For the first time, Harry looked surprised.

"Yes, sir. That night in the empty classroom, you told us you'd take Irene in for questioning in the morning, right after breakfast. Sherlock said you told us so that we'd know when to search her rooms."

Ron found this extremely funny. "You've got to admire the kid's nerve," he laughed.

Harry, on the other hand, didn't crack a smile. "Molly is still unconscious," he said quietly. "I hope you boys realize now that this isn't a game."

John didn't have to fake an expression of deep guilt. "We do, sir."

Harry sighed. "Is there anything else you can tell us?"

John hesitated for only a second. "Actually, there is. Sherlock and I saw Molly right before she was taken to the hospital wing, and Sherlock found…well, a clue." John felt ridiculous putting it in those terms, like they were playing a game, but he didn't know what else to call it. "Something that he thinks will lead us to Irene's accomplice."

Ron and Harry looked at each other.

"What makes you think Irene had an accomplice?" Harry asked.

John was slightly taken aback. "Well, she was with you two when Molly was attacked, right? So she couldn't have done it herself. She must have guessed what we were planning when you asked to talk to her, and arranged for someone else…"

He trailed off when he realized that Ron and Harry were both shaking their heads.

"We grabbed Adler as she was leaving breakfast and took her straight to our interrogation room," said Ron. "She didn't have time to contact anyone."

"We eliminated her as a suspect the moment we found out about Molly," Harry added.

Now John was completely thrown for a loop. He hadn't even considered that Irene might not be involved at all.

"But…but how did the attacker know that Molly would be searching Irene's room, if Irene didn't tell them?" he asked.

"That's a good question," said Harry. "Who knew about the plan, aside from you, Molly, and Sherlock?"

"No one. I didn't tell a soul, and Sherlock wouldn't tell anyone who didn't absolutely need to know. And Molly…"

Suddenly, it clicked.

"Bloody hell," he said, more to himself than anyone. "Why didn't we see it before?"

"What?" Ron and Harry asked in unison. But John was already bolting down the corridor.

He reached the Hufflepuff dormitory in record time. Mercifully, it was early evening, so most students were hanging out in the common room. He burst through the secret passage and made a beeline for the far corner, where he knew a gaggle of first year girls that usually included Molly would be sitting.

"Molly's Slytherin friend," he said between gasps. "What can you tell me about him?"

The girls look at one another, startled.

"I guess he means that second year boy," one said uncertainly. The others nodded.

"So you know him?" John asked.

"We know of him," sniffed another girl. "Molly's the only one who really knows him. How she got to be friends with a Slytherin, I don't know."

"Yes, but his name. Do you know his name?" John was vaguely aware that he must seem quite mad, but he couldn't care less.

"James, I think."

"No, it's Jim," said a third girl. "Jim Moriarty."

John felt a sudden urge to grab the girl and kiss her, but he resisted it.

"Thank you!" he said. Then he was off again.

He was halfway down the corridor before he realized he had no idea where the Ravenclaw common room was. It turned out to not matter, for at that moment the person he was looking for came around the corner, nearly running straight into him.

"I've solved it!" Sherlock said triumphantly. He waved the watch in John's face. "I've cracked the code! We'll know who attacked Molly by midnight tonight!"

For the first time in days, John grinned.

O0O0O

Author's Note: Once again, I'd like to thank all of my lovely readers for sticking with me. Sorry for the long, unexpected hiatus between chapters seven and eight. Updates should be more frequent now that I'm out of school.

By the way, if you want a sneak peek at each chapter a day or two early, you should follow me on Tumblr. The link is on my profile page.