Chapter Four

"I knew she was cheating on me!" Davis said through gritted teeth once we'd sat down uninvited across from him. "I just knew!"

"You and the rest of the school." I snorted. "But never mind that now! We want to know if anyone had any motive to kill her."

"Besides yourself of course." added Sherlock. Davis glared at him and banged the fist holding his wand on the table.#

"And what's that supposed to mean freak?" he hissed. I leant back a little and Sherlock rolled his head to look at Davis.

"You have the most obvious motive for killing her." he said. "I'm surprised it didn't cross the minds of the Aurors, dull witted as they are it was a big thing for them to miss. And you can put that away because attacking us will only cast further suspicion on yourself."

Davis' face slackened and he began to shake. Sherlock looked wholly unconcerned.

"Lucky for I know you flunked your potions OWL so couldn't possible make a potion like the Draft of Living Death without blowing yourself up. So, who else had a motive?"

"No one." said Davis pathetically. "She was always winding people up, gossiping and everything, but not enough to make someone want to kill her!"

"Well she must have gossiped about something worth killing for." said Sherlock impatiently.

"It might have something to do with Rachel." I said and Davis' head jerked up.

"What her mum?" he said and my eyes grew wide in excitement.

"How do you know that's what her mum's name was?" I asked eagerly. "Mr Potter couldn't find a record of her parents."

"Kelly had this ring with Rachel engraved on it." Davis shrugged. "She kept banging on about it belonging to her mum, she never took the damn thing off!"

"This is a waste of time." Sherlock hissed, dragging me out of my chair and away from Davis.

"Sherlock its her mother! How can you think that's not important?"

"Oh come on! She wrote that as she was dying, she would have been in pain, Rachel is a code for something I know it!"

"Or it could just be that she was thinking about her dead mum!" I snapped.

"But she died years ago why would she still be upset?" asked Sherlock. He watched my exasperated expression for a moment before saying, "Not good?"

I shook my head and Sherlock blinded, before shaking himself irritably.

"Forget about Rachel, we need to think who could kill Kelly. The murderer would be someone who hunts in a crowd, who can move around the school unseen, in plain…sight."

Sherlock trailed off and he stared into space for a while. Then he said quietly,

"Oh that's clever, yes very clever, and no one would suspect…"

"Suspect what?" I asked sharply and Sherlock seemed to snap out of his trance.

"I, I'll tell you tomorrow. I think I'll just go to bed."

"What?! But it's not even ten yet!"

"I hate it when John drags me to these things, I just want to go to bed!"

And with that he hurried out of the room. I watched the wall melt into place behind him before sighing and turning to look for Lilly. It was only a few minutes later that I realised someone had been standing outside the door when Sherlock left, and how stupid I had been.

Argus Filch was standing in the shadows outside the Room of Requirement waiting for Sherlock. As the wall closed and the loud music and talking was cut off behind him, Sherlock gazed at the middle aged caretaker in his shabby over coat and shuffling shoes.

"Kelly Trent and Carl Powers worked it out didn't they?" he said coolly and Filch's mouth stretched into an unpleasant grin.

"They always were too clever for their own good." he wheezed. "And they paid for their nosiness."

"How did you get them to go with you?" Sherlock asked and Filch laughed.

"Not here Mr Holmes, how about somewhere more secluded eh? Set the scene why don't we."

Sherlock didn't even hesitate; he followed Filch without a care in the world. Filch took him to a lonely tower overlooking the lake. At the top of the narrow winding staircase was a dusty room with a table and two chairs facing each other. On the table were two bottles, full of inky black potion.

"Of course I don't get the little brats myself." said Filch casually, lighting the candle with a match. "Can't perform the Imperious Curse. You know why I suppose?"

"You're a squib." said Sherlock impassively, gazing around the threadbare room. Filch shot him a poisonous look.

"You're another one who's too smart for your own good, but at least you don't laugh. That girl laughed, and that stupid boy."

"So someone brings them to you, takes their wand and leaves them to be punished." Sherlock deduced. "Who takes them?"

"Ah now, that's not for you to know sunshine. I saw you, strutting around the school like you owned the place, you and your little backing singers. Thought you were so clever didn't you?"

"Oh I don't think, I know." said Sherlock and Filch grimaced.

"Well you're not that smart see!" he growled. "Now sit down, we're going to play a little game."

Sherlock sat and so did Filch. Sherlock's eyes were flicking between the two bottles, calculating, deducing.

"I suppose your contact provides the potion as well." he said. "My my he must be bored."

"Something you two have in common." Filch sneered. "He pays me for every kill I make, I intend to be rich when I retire and you snot nosed little brats have had this coming for years."

"So one bottle contains poison the other a fake, how do you make the students drink one?"

Filch took a gun out of his pocket and pointed between Sherlock's eyes. Sherlock looked fleetingly disappointed.

"Ah, dull." he sighed. "You can't use magic so you resort to muggle weapons. Not exactly ingenious."

"Does the trick." Filch shrugged.

"No it doesn't, I took advanced muggle studies in my first year I can tell the difference between a real gun and a fake."

"Yeah but I wouldn't need it anyway would I?" said Filch, stowing the gun away. "For the same reason I didn't need to take your wand. You just want to prove just how clever you are, you'll pick a bottle without a fuss."

"One thing I don't understand is why the choice?" asked Sherlock, studying his fingernails. "Why not kill them and be done with it?"

"My contractor." Filch explained. "He wouldn't pay if it was dull, and this way I can make it look like suicide. But enough dawdling Holmes, chose."

Sherlock dropped his eyes to the bottles again and after a moment, tapped the one on the left. Filch leant forward and stared at Sherlock shrewdly.

"Care to test it?" he asked softly.