The Fate of the Watershed Four

For a brilliant Ravenclaw, my friend Sherlock Holmes has talked me into some truly stupid things.

Dropping veritaserum in headmistress McGonagall's pumpkin juice before she addressed the first years. Stealing an entire shipment of school laundry to rescue a house elf. Challenging the Centaur tribe to shogi, Japanese chess, for the fate of a broken TI-89 calculator. And it was only our fifth year. Good times.

Still, nothing prepared me for the day Sherlock and I found ourselves locked in a makeshift clubhouse submerged in the Great Lake.

Swimming with wands in gritted teeth, we approached the flickering ember of light adrift in the black-green water choked with seaweeds and more. Jagged, waterlogged wood planks abutted riveted metal around small porthole windows aglow with a weak orange light. Candles? Overall, it was an ironclad, upside-down tree-house in the kelp with a Titanic-sized chain leading into the crushing depths. Sherlock pulled himself hand-by-hand along the sludge-coated wood to a submarine hatch on the underside, and we entered as our bubble-head charms faded.

He stepped, wand up, standing at his full height in an open room with hollows on four sides, just a step above the hatch in the floor. Cots, bedtables, cabinets and upended furniture lined three hollows. A squat table with one central leg stood in a corner near Sherlock. All around, the walls and floor were full of Quidditch player pin-ups, potion supplies and empty butterbeer bottles.

"Ingenious. Impervius charm. Cast on the building materials. Must have taken weeks. Assembled underwater, though. See the seeping in the joists? Wonder what keeps the pressure from crushing it. Something forced them to speed up construction. Weird. Got your breath back? Close the door if you don't mind."

I eased the heavy iron hatch into place slowly, but the impervius-charmed metal jerked out of my fingers.

"Sherlock..." I said warily. Instinctively, I gave the hatch a tug, and an electricity-laced utility pole swung by a troll knocked me on my wizard butt. "Think we're locked in," I groaned.

"John! Are you all right?" Sherlock crouched over me, waving smoke out of his eyes.

"I'm supposed to be studying for a Muggle Studies test tomorrow." I coughed.

He scanned the hatch with his fingers. "A trigger-based relashio charm and something, something else." He shook lake water out of his shaggy hair. "What are these markings?"

Sherlock flicked his dark, polished wand at the hatch, the only apparent way out of the musty room about a fathom underwater. A paper scroll unfurled from a box nearby, revealing three wands on leather thongs and a fourth empty leather strap.

"Oh, good. We're locked in and the only way out is a puzzle. Just like getting into the Ravenclaw common room," he said with a smile.

"But that bronze eagle stumped you yesterday."

"For the last time, naming one actor from the Lord of the Rings movies is emphatically not a riddle. It's barely a trivia question," he said with a scowl at me.

"Still stumped you, though. We had to wait for a Ravenclaw with a data plan."

Then a mini-earthquake interrupted our banter. The entire clubhouse rocked like a fishing boat in a monsoon. The clatter of broomsticks and clink of bottles settled shortly.

"Sherlock? Was that you?" I asked, looking at his wand.

"Selkies," he said under his breath, his eyes on dark dribbles of lake water drooling down the walls and pooling at the hatch in the center of the room. "We don't have long, John. Talons up."

"Right."

That was Sherlock's way of saying it was time to get to business.

Quoting the Ravenclaw cheer in the Gryffindor common room bothered my housemates, but it was different for me. It usually meant we were going to get into some good trouble or that we were about to get out of it. Besides, Sherlock cleared the Gryffindor Common Room every time he crashed it.

Actually, "Talons up" was the first sign Sherlock was going to take a case that had us dozens of feet below the surface of the Great Lake. Sherlock had dismissed a dozen cases of lost wands and was aching for a decent case.

At Hogwarts, it's a school tradition to say you're afraid for your life at least once a year. However, it's a little more uncommon and tragic to be the only surviving member of your friends.

The lanky, blond, sixth year Hufflepuff's case was especially irresistible to Sherlock once he said one of his friends was rendered utterly magicless. To some wizards, that's worse than death.

Filigree Carver, a Hufflepuff, came to Sherlock and I yesterday because he thought a Merpeople curse was going to kill him or worse. Last year, he was one of four friends from each house. Over the summer, a cleft-chinned boy, Chester Marlborough from Gryffindor, drowned when a freak car accident dropped his family van in a river with his whole family in it. That was a week after bespectacled little Simon Yeager from Ravenclaw was killed by a bad sushi poisoning. The newspapers covered it, and I knew Sherlock, who studied every murder in the Daily Prophet, hadn't missed it.

In all cases, nothing suspicious had been turned up by Muggle police or the Aurors.

Then there was pug-nosed Slytherin Moishe Pinkleworthy.

After a week into this semester, Moishe was put back on the Hogwarts Express when he apparently couldn't use any magic. (With a name like that, I figured he'd stop going out in public long before his sixth year. But oh well.) His wand, useless, and even potions were nonreactive. When he left, word got out that the Pinkleworthy family's wealth was apparently threatened and needed special home-based training for Moishe.

Sherlock, a halfblood himself, had a better understanding of the Muggle world than I did. Paying rent, driving licenses, calculus classes, smartphones and job resumes. His steepled fingers shivered.

Filigree wouldn't go to the professors. As he put it, he blamed himself and was sure the professors would, too. The Merpeople must have been upset with the clubhouse Filigree, Chester, Simon and Moishe built. There, they stockpiled spare butterbeer, prank supplies from the Weasley's Wizard Wheezes and once spent an entire Christmas under the Great Lake. Evidently, too much noise and garbage and not enough neighborly grace doomed Filigree and his friends.

Filigree said a few Merpeople had attacked them at the end of the previous term, and now, well, most of his friends were dead in water- or fish-based deaths – and one relegated to a status many think impossible.

Filigree needed Sherlock's special kind of help. To potentially negotiate a truce with the Selkies. Or uncover a way to undo the damage to Moishe. Or at least, stop the curse before it killed Filigree himself. Knowing Sherlock, he'd try to hit all three. Filigree wanted us to go straight to their clubhouse.

Sherlock said "Talons up," and marched straight to the Hogwarts library instead.

That was yesterday. I only saw him again this morning, when he talked me out of Quidditch practice to dive into the Great Lake with him – and apparently get locked into rickety clubhouse the Selkies intended to crush like a butterbeer can.

Now, as I felt a second, earthquake-inducing strike from the Selkies, I couldn't help but doubt Sherlock's plan. After all, his pep talk this morning didn't mention death. Maybe we should try to outswim the Merpeople.

But Filigree counted on us – perhaps for his life.

I cleared my throat. "What's the plan?"

"Think," Sherlock said in that absent, automatic way as he turned from the three-wand lock and began to divine the mystery's solution from the underwater clubhouse. "Something's missing from this picture."

Built out of wood and iron, the room felt like a sailing ship's crew cabin decorated by teenage boys. In three hollows a step up from the hatch hung now-swaying lanterns, still in motion from the last Selkie hit. Posters of three Quidditch players dominated the highest wall. A dark porthole on a bare wall swallowed light – and I didn't dare look into the dark waters now, in case I drew the Selkies' attention. Irrational, I know, but maybe the impervius charm was probably weaker on glass. Papers strewn across the floor, showed water spots. One full bottle was strapped to a board in the corner while several empties rolled freely on the floor.

The wood joists and iron-riveted joints creaked and groaned.

Hold it together, John.

The floor, wooden also, at least felt sturdy. A central table, no, a storage crate with a round board on top, occupied the main floor space. Around it were cots, three of them, with a nest of clothes around each one.

"Ugh. Who could sleep here?" I shook my head.

"Who did, indeed, John." Sherlock said with a nodding look. "It's plainly part of the ruse. The real question is figuring out what Filigree wants dropped to the bottom of the Great Lake. It's not their recipe for copying bottles of butterbeer."

Sherlock cast his wand out. "Violumos." And from the tip of his wand came a faint purple light. Dots and smears on the table, previously invisible, appeared under his wand in bright green. Smears. Fingerprints. Trace stains. But from what?

"What are you talking about? What does who want at the bottom of the lake?" I stared down at the table. A green stain from an old drink spill filled a quarter of the round tabletop – and near the center of the table, the green stain ended in a sharp corner. Either something square had blocked the spill from spreading, or...

"I'm talking about the real secret Filigree is hiding. Our client has set us up." Sherlock's long fingers searched the center of the table and found a hidden panel. The black light went out. "Wingardium leviosa."

The whole table seemed to shake, but nothing lifted into the air as it should have.

A drop of water fell on my nose. "Is his secret under the table?"

My friend leveled a smirk at me. "There is no Merpeople curse. Never was. Help me lift the table. On three?"

I nodded. "Three. Wingardium—"

That's when the next Selkie strike hit. So, it's no wonder it took both of us off-guard entirely. Furniture rattled, empty butterbeer glasses clattered and Sherlock's feet went out from under him. For the second time in less than 10 minutes, I hit the floor and groaned. Somewhere, I heard a hiss of pressurized water.

"Oh, for Merlin's sake," Sherlock muttered, as he pulled himself to his elbows. He pointed his wand at the table. "Reducto!"

Chips of the secret panel erupted toward the ceiling. Instead of falling to pieces, the table broke in half, as if split by a giant ax.

The crate and table had been crafted out of a solid piece of wood. Hunh, weird. The only time I'd seen something like that was near the Hufflepuff common room entrance. An older boy had grown a chair from a walnut.

A faux plate had apparently been grown into place to cover a cavity inside the object. From the cavity, a picture frame in glass clattered out.

When I picked it up, I recognized Filigree, younger and marked by acne, with three other boys. They were posing, wands up, at the edge of the lake beside a hatch door. The figures didn't move, unlike most wizard photos. I showed it to Sherlock.

"A Muggle photograph? Who would keep it there?"

"Perfect, John!" Sherlock took the picture, glass frame and all, and threw it against the metal. Instead of shattering into pieces of glass and wood, it ricocheted up, off the wall, and back into his hand. "Impervius charm, again. Fits the pattern, doesn't it?" Sherlock said with a wink at me.

"What? Time for you to impress me with an explanation," I threatened with my wand in Sherlock's face.

"Nice wand. Some say it's the vital conduit for wizards and magic. Which wand did Filigree have yesterday? Observe the wands, I always say," he said, wagging a finger as he went to the hatch lock. (I've never heard him say that, by the way.) "Who's missing now? Four hollows for beds. Four wands were here. Four leather straps for four wands with the door, but three cots? Three athlete posters? Who's the odd man out – and why?"

"You're not making sense. What do beds have to do with the impervius charm?"

"Charms are stronger when two cast it. This is about power. Imagination is an investigator's greatest tool. So, John, let's imagine for a minute."

The hiss of water got a bit louder. "Can we imagine faster, please?"

"Fine. Where would you hide your leftovers?" Sherlock began to pace. "You've tested a fringe magic theory, and you've had to do it a lot. No one leaves wands around. They'd all notice." Sherlock tapped his wand on an empty butterbeer bottle on a bedside table – and then rushed at the bottle of butterbeer I saw before, the one taped to a woodplank. It looked like new. "Unless you practiced the Gemino curse every weekend."

"Gemino? But still, the Doubling charm is advanced magic, Sherlock," I said, going to the table he had split in half. As a nervous tic, I started running my fingers on the split wood. "Unless you're really good, as in Auror good, the copy isn't going to be perfect."

Sherlock gasped. "That's right. Don't drink the butterbeer, then," he said, smiling. Sherlock's reverie continued. He circled the room, approaching the hatch. "So, you've nicked students' wands and replaced them with a copy so you can experiment with casting using groups of wands. Which wands work best? You don't know until you try. It's harmless because most of the useless originals get back to the students – except when they don't. What if, John, what if you suddenly had a Gemino of your own wand? But you didn't know it."

"Good thing I've got dragon heartstring. At least it would be copied. Still, I'd think I was losing my touch. Are you saying that one of Filigree's friends was stealing wands to, what, cast stronger spells?"

"Wands make the wizard, John. Not Filigree's friends. Filigree himself. And what if the best wand he found belonged to one of his friends? With the right pair, his Gemino would be strong enough to make duplicates of anything, except itself. The right wands would make an underwater clubhouse withstand the water pressure in the lake. Maybe even Selkie attacks."

Just then, cannon-force explosions shook the air and rocked the walls, knocking us off our feet. One lantern winked out, leaving Sherlock and I in a campfire-yellow glow as we held to the walls and floor. The crashing noises around had a new tone, one that ran chills up my spine. Trickling water. Pools collected at our feet.

In a rare moment, Sherlock and I came to the same conclusion at the same time.

"You had to say 'maybe'!" I thundered as I got to my feet.

Sherlock seized the hatch's paper scroll. Strung to the top of the hatchway were three wands: a straight ash, a notched cherry, and a crooked walnut. A fourth strap. Sherlock placed his own in the strap. Nothing happened.

"It's a wand lock. Alohomora in the right combination of wands. Open the door without the combination and, well, relashio. The point is, use the right wand."

"What happens if you use the wrong one?"

Sherlock ran his fingers through his hair. "Not sure. Best to not get it wrong, then."

I took a step up out of the now-completely-wet hatchway, even as the water rose to follow. "There's probably not enough time for curiosity anyway. Are those stolen wands?"

Sherlock flicked his fingers along them. "Most likely copies of Filigree and his friend's wands. Have to find the right resonance with the hatch."

"Definitely not the Slytherin. Too dynamic. The Gryffindor's maybe. First would be the Slytherin, unless the Ravenclaw devised the lock. Probably, given the complexity. Who went to sleep first? They had to leave in the same order, every time, and who would go last? Who was last to stand up? All the cots are on the far wall. No one sleeps by the hatchway. No one does now."

Sherlock said once that having me around helped him. Saying aloud all his thoughts, even if I couldn't follow them all, seemed to speed up his process. What if this time he wasn't going to be fast enough? One more hit from the Selkies could pop this clubhouse like a bubble.

Sherlock, staring at the wands, was waist-deep in lake water. I unconsciously stopped breathing.

"The wands, the butterbeer. Copies," he muttered. "The Ravenclaw, sloppy but clever, created the mimicking plate for the butterbeer bottle. Free drinks any time. Makes you a popular friend."

"Yeah, everyone loves having a Ravenclaw for a friend," I said, rolling my eyes.

"But whose wand comes first?"

"Maybe it's Filigree's? The walnut one from the picture?"

"Filigree had an ash wand yesterday!" Sherlock shouted back, then muttering to himself, "It would have to be a simple spell like alohomora for the wand lock to work."

"But Filigree doesn't have the ash wand," I waded toward the hatchway beside Sherlock.

"I know ash! I remember Filigree's wand," Sherlock said, frustrated.

"But he has the walnut wand in the picture!"

Sherlock's eyes shot wide with understanding. "Oh! That's the answer." His long fingers brushed all four wands, slow and seeming not to care that we were about to be drowned and skewered by Selkies.

"What is? Which wand is the right one?"

Sherlock's eyes met mine. "The right one is the missing one." He slipped his blue and bronze tie off his neck. "Take hold of that picture, John, and whatever you do, don't let go. Get near the table. It'll provide the best cover while the implosion obscures us from the merpeople. We have to catch them off-guard."

Implosion? "Wait. Wait!" I scrambled in my pockets for my own wand.

He snapped the wands, including his own, off of the paper scroll, swept their tips down at the hatch door, and bellowed, "Reducto!"

I gasped microseconds before spouts of black lake water engulfed my best friend from every direction. "Sphaeraeris!"

In the next blink of an eye, the room turned to debris and bubbles.

I could see nothing, but I felt everything. Sharp pokes and prods from every angle, icicles piercing between slimy tendrils and leaves. My knuckles strained on the picture frame hugged to my body, and it stayed in my grasp. The table, on the other hand, had become a buoyant force. My fingers slipped on it as if it was a train that's left the station, and I fought to find one half rushing to the surface.

Then the bubble haze faded from my vision. Dark water below and green above. Where's Sherlock?

Below my feet, I saw his pale skin and white dress shirt fading into the depths. Below his closed, listless eyes was the bubble-head charm I placed.

My own lungs pressed against my ribs, begging for air.

Kinda nice to see I finally got that charm to work. It wouldn't do him any good if I let him sinnk to the bottom of the Great Lake.

I released the table, kicking furiously against all of my survival instincts to catch up with my sinking friend. His grip still held the wands, loosely. Stronger charms if cast together? Fine. Let's try my favorite.

I squeezed my spare hand around Sherlock's, adding his four wands to mine, and burbled out, "Accio table!"

Snakes of seaweed, creeping by my face and arms, slipped back into the darkness. I felt us rising toward the light green. The surface wasn't that far away. Or was it?

The only thing closer than the surface were the Selkies.

Silver scales flashed past my upward gaze, and the shadow of a trident crossed my face.

Behind it, I saw the broken circle of the table, closing in while pulling our weight up. I could get Sherlock to it and then turn and defend us. I just need a few more seconds to get him to our improvised life raft.

Four razor-sharp nails pierced my heel through my sock. One of them had me. I started kicking – and didn't notice Sherlock doing the same. His grip strengthened on the wands, and he writhed, as if in a panic. Calm down, or you'll kill us!

Then he kicked me square in the chest, compressing me with the impervius-charmed frame. My lungs went from loan-shark vicious to mafia-boss murderous. But a Selkie, approaching from below, zipped between us and struck the table face-first.

Sherlock grabbed my hand and helped me get to a table half. Nothing stirred around us in the now-cloudy green water around us. Tunnel vision closed in as we held on, feebly kicking up. In the wood grain of the table, I saw speckles, like opalescent glitter, pure white, surrounded by round circles of wood a different color than the rest of the table, exposed in the broken wood. Huh. Is that unicorn hair? My brain felt stuffed with straw.

One geologic epoch later, we broke the surface.

A few choking gasps later, I swam the table halves and the picture to the beach where our robes and shoes were. Debris from the clubhouse bubbled up around us, including one unopened bottle of butter beer.

Also waiting at the lake shore were a crowd of students and professors. Headmistress McGonagall stood behind Filigree Carver, who frenetically pointed at us, shouting, "There they are! They're the ones with the stolen wands!"

Taking tea with the Selkies sounded like a great idea now.

Instead, we swam the broken table halves to the rocky shoreline. Sherlock took long sloshing strides to the rocky shoreline, his arm outstretched to Filigree. I heard his smile as he said, "Congratulations! I think you're only the second person to successfully led me into a death trap. Truly, I hope my next one is as well thought out."

Filigree scoffed, slapping Sherlock's hand away.

"Get a towel on them. Mr. Watson looks as blue as chilled blueberries. Exaresco," she said, blasting warm air to dry my hair. The headmistress cleared her throat, which couldn't clear out her Scottish brogue. "Mr. Holmes, I've just heard an alarming story from Mr. Carver, including an accusation of thievery and wanton destruction."

"Professor. I'll grant you those are my modus operandi," Sherlock said, eliciting a few giggles from the students gathered. "I'm also prepared to consider taking his accusations somewhat seriously."

"Well, that's a relief," she said, flatly.

"After he answers just one question. One question," Sherlock said with his palms open.

Filigree's voice squeaked. "Why haven't you taken his wand and expelled him, professor?"

"Save your summary judgment, Mr. Carver," the stern-lipped headmistress said. I cast the hot-air charm on my socks, knowing my friend was prepping for some big speech. "Ask away, Mr. Holmes. And don't make me regret it."

Sherlock circled Filigree. "May we see the wood your wand is made from?"

The nervous Hufflepuff froze.

Sherlock pointed. "Oh, look. There, it's in your pocket. Here, let's show everyone," he said reaching for Filigree's wand himself. Before Filigree could cry out, he found himself wrestling with Sherlock Holmes.

Their struggle ended just as suddenly before McGonagall could shout anyone's full name. Filigree pushed my reed-thin friend back, who windmilled his arms, slopping bystanders with lake water. I jumped to his side, and Minerva took a broad stance with hands projected between both the scowling Filigree and the weirdly cheerful Sherlock.

The rustle of students surrounding us stopped silent.

A straight ash wand clattered on the rocks. Filigree scrambled to pick it up.

"Mr. Holmes, I've had it with your insolent theatrics," the headmistress shouted – and her words stopped short. "What's the meaning of this?"

Sherlock Holmes also held up an straight ash wand, the mirror image of the one that Filigree now leveled inches from my friend's face.

"Step back, John," Sherlock muttered.

"That's enough," the headmistress threatened, her hands reaching for her own wand.

"Not a chance," I said, reaching for my own. Even so, McGonagall and I would be too late to the party.

"I'll be just fine," he said with a steely gaze and a smirk at Filigree. Then, in a raised voice, Sherlock enunciated every syllable of "Petrificus to—"

But he never finished. Filigree squealed out a fast, "Expelliarmus!"

To her credit, Minerva McGonagall barely flinched. After all, she stood between two dueling wizards, armed kids to her mind, and still learning the rules of forces most people considered impossible. My own noise was so high pitched I was always able to claim it came from a Slytherin first-year girl behind us.

However, instead of the bright flash or beam of magic, the charm did nothing.

Sherlock's hair fluttered back as if he had just opened a window. And then he smiled broadly as if seeing the sun.

"Losing your magic touch, Filigree? Maybe your friend could empathize."

Filigree shouted the charm a few times in quick succession, each time tossing less and less wind in Sherlock's face.

Gasps and murmurs from the students rose as McGonagall gathered herself to her full height.

In one move, she snatched the wand out of Filigree's hand and took the wand Sherlock offered in two fingers. "The demonstration is over, I presume? Now, will you explain why we're all at the lake and why Mr. Carver's wand is as useless as wheels on a broom? Before I decide to expel the three of you."

"Oy. What did I do?" I protested.

Sherlock cut in. "Only the most important thing, John. Protected the evidence," he said, lifting the charmed picture from my hands. He handed it to the headmistress.

"You're holding the wand of Moishe Pinkleworthy, professor, and an impotent duplicate created by Mr. Carver. This photo from last year, and I presume any other previous photos Filigree hasn't destroyed will show that he possessed a dark walnut wand in previous years."

McGonagall's eyes flickered over the photograph and back to Filigree.

Sherlock picked up a towel, drying his hair as he continued. "Filigree Carver has been experimenting with combining wands to cast stronger and stronger spells. We all know two wizards are stronger than one. Filigree's also discovered that, with the right wands, one wizard can be stronger than two. I assume his true wand is also on his person somewhere, but I couldn't find it my brief search you just saw when I pickpocketed the true Pinkleworthy wand."

Sherlock strode to the table halves. "A brilliant discovery, truly worthy of House Ravenclaw. But he started taking wands to test with his own. Sometimes he could return them, if it failed, but what if it didn't? The Doubling Charm, perfected over countless weekends in a secret clubhouse with his friends duplicating butterbeers, gave Filigree all the wands he could want."'

"It's true, I've seen it. The clubhouse, I mean. What's left of it is floating in the Great Lake?"

"What?" the headmistress said, aghast at another mess to clean up.

Sherlock cleared his throat, regaining the audience. "Except that they didn't always work as well as the real thing. Unicorns are particularly magic-resistant. Maybe their hairs never duplicated. In any case, Filigree hid a stash of real wands after slipping dozens of powerfully Gemino-charmed fakes to students. A stash, by the way, that John Watson and I discovered hidden in this table, magically grown with a signature Hufflepuff botany charm."

Students crowded to the table. Filigree, stared, his face blanching as Sherlock went on.

"I suspect sometime near the end of the last year, his experiments included the wands of his friends' – and normally harmless situations turned surprisingly fatal with impotent wands. And the worst fate, well, Filigree knows what that's like now, don't you? I also imagine he never thought he'd be confronted after he sent us to his friends' clubhouse-turned-deathtrap after he locked us in and somehow provoked the Selkies. A little bit of basic reading, and it's clear Selkies have no capacity to curse or otherwise wield magic, John." Sherlock stepped to face Filigree. "I knew his story was a sham less than an hour after we met him yesterday."

I frowned. "You did? So, why did we go into the lake?"

"To find what we found, John." Sherlock turned to Professor McGonagall. "We've recovered most of the stolen wands and pinpointed a young wizard who likely was responsible for the deaths of two Hogwarts students and the inadvertent expulsion of one more."

"Hey!" bellowed one deep-voiced student. "My wand's split in two. Did you break this table?"

"Mine, too!" came a few more cries.

Sherlock rolled his eyes. "I said 'most.' And we've also made public a novel piece of magic and wand theory. That should count for something," he said proudly folding his hands behind his back.

I put my palm to my forehead. "For a genius, you can really..."

"I agree, Mr. Holmes. That's 50 points for Ravenclaw," McGonagall said, defying belief.

"... get away with anything."

McGonagall continued, "Now, 20 points from Ravenclaw for instigating a fight, even if to prove a point. And 40 points from Ravenclaw for littering the Great Lake. Finally, 40 more points from Ravenclaw for damaging student wands, even though it seems you've recovered a few. Let's hope it's a net gain, on the whole, for the students."

Ah, now that's the Professor McGonagall I know. Sherlock grimaced as he continued drying himself with the towel.

"But points aren't everything. Filigree Carver, I take it from your actions this morning, that this is true? Mr. Holmes did not, as you told me in my office just five minutes ago, attempt to steal your wand last night as he appears to have a duplicate here." She clapped a hand on Filigree's shoulder. "We have some owls to send, young man."

Professor McGonagall ushered the students back toward the castle, commanding a few Hufflepuffs to free the wands from the table. The crowd channeled back to the paths through the woods back to Hogwarts castle.

"Any points for Gryffindor for surviving the merpeople attack?" I regretted it as soon as I said it.

"Oh yes. Thank you for reminding me. 10 points from Gryffindor," she said with a withering look. And before I could ask, she added, "For going along with this tomfoolery."

I had just dried my socks when I heard footsteps on the rocky shore. A tall boy emerged from the last of the gathered students. He was thick in the neck with a broad forehead, as if someone mounted a giant light bulb to a pole, painted on a menacing grin, and dressed it in Slytherin robes and a green tie.

In four years of adventures, I never quite warmed up to Sherlock's older brother. Maybe it was because of the old Gryffindor-Slytherin rivalry. It was probably because he was a prick.

Sherlock, donning his robes, and wrapped the wet towel around his waist. "You've left the Great Hall, I see. House elves out of bread pudding?"

"Such witty repartee after your derring-do. It sounds positively exhausting." Mycroft said the last word slowly, rolling his bulbous eyes around the shaded wood, bored, as if he knew what he'd see before he saw it. "I merely came to see what punishments awaited your good deeds. You know what they say."

"Maybe we'll charge admission next time." I turned to Sherlock and asked, "Exaresco?"

"No thanks," and he tossed the wet towel at Mycroft, not looking to see it hit the Slytherin's usually pristine apparel with a flat slop.

We started back up the path to Hogwarts.

"Sherlock..." His thready voice drawled. "I've come prepared to make amends. To pay a penance. Mine and yours."

Sherlock stopped, his face inscrutable. "Is that so?"

"What's he talking about? Sherlock?"

Beside me, Sherlock slid out his scarf and retied it around his neck. "I'm listening."

Mycroft flitted his eyes at me, then went on. "The broken or damaged wands. I'll pay the reparations to Ollivander's. In exchange, we let certain exchanges pass, water under the lake, as it were. I clear your debt, and you clear mine."

My mouth fell open. Ollivander's was costly. My parents certainly didn't have that much money. And Sherlock's wizard mom and Muggle father weren't exactly swimming in gold. Mycroft, the best dressed sixth year with the Sherlock's parents, had somehow acquired a miniature fortune that kept him with a finger in a lot of pies. Sometimes literally.

Sherlock made a minor show contemplating Mycroft's offer.

Finally, he turned up the forest path with his thumbs sticking out of his pockets. "No."

I could hear Mycroft's smile turn to a sneer. "A box of accidentally destroyed books, Sherlock. Balanced against the high price of precious wizard wands and your respect amongst your classmates."

"Target practice on my Nancy Drew collection. You'll pay for several Christmases more."

"You know you belong in Slytherin. You're a rational. More so than the other eccentrics in your puzzle-loving house. The Slytherins are about making a difference." Mycroft's voice grew louder as we walked, going uphill and rounding a corner in the woods.

Mycroft's tone shifted, and I felt he was addressing me. "You do realize the game he plays, don't you? He may have chosen Ravenclaw, but the Sorting Hat's pronouncements are also a prophecy of a kind. Ask yourself, young Gryffindor, whether the young man beside you has ever cared for one client. Has he cared about anything but the problem?" Mycroft's voice muffled and faded away.

After a minute, we neared the stone walls of Hogwarts. A change of clothes sounded nice. "Do you think he's still talking?"

"Not sure," Sherlock grinned. "There's no one in the forest to hear him."

Passing students stared at us chuckling to ourselves in our wet clothes, Sherlock still barefoot and carrying his shoes.

It had been a short trip, all told. About an hour and a half. We had missed only an afternoon, and dinner was coming soon. At one point today, I thought we were both going to die. We pulled through. Sherlock cracked the case. I pulled him out of deep water, literally. Filigree Carver's case felt disturbing, and the laughter of friends was good. In the end, that's what Filigree had traded away.

Giving his friends faulty wands to gain more prowess, maybe even get through school with the highest marks – only to learn about the terrible fates they befell. And he chose to either destroy his secret rather than help another friend, even if he was a Slytherin. From a Gryffindor's perspective, what happened was horrible. From a Hufflepuff's perspective, it was unthinkable. They generally were the most decent of people, the greatest friends.

Then, I noticed something. "Sherlock, your tie. The colors must have run in the water. The bronze looks almost gray now."

"Bronze, gray. Red. Blue. Green. Yellow," Sherlock said, casting his eyes into the crowd.

I couldn't tell from his gaze whether he was contemplating how students from all four houses forged a bond to achieve a relatively impressive project together – or the fact that one had turned from what his house valued most and destroyed it all.

"They're all just colors."

+++Author's note+++

Thank you soooooo much for reading! I'm having so much fun with this idea, placing Sherlock in this setting and watching the characters interact. Truly, I had no idea McGonagall would be such a hoot to watch with the wizarding world's greatest living detective.

I intend to write Hogwarts in an episodic series of short story cases, akin to the Sherlock Holmes canon. For me, the fun part is daydreaming the tangled puzzles with JKR's world. Plenty, plenty of cases to follow.

Want to hear a teaser on the next one?

As fifth years, Sherlock and John have to wait a while before they can get their License to Apparate, the wizard's teleportation. But it's useless in Hogwarts because of a long-standing enchantment that protects the school and its students from invaders and themselves.

But when one student very publicly disapparates from the Great Hall during a visitor's demonstration of Death Eater methods - without reappearing anywhere, Sherlock and John pick up the case and investigate a potential new threat to all of Hogwarts students. But how do you help a client who's already vanished into thin air?