Professor Granger was waiting for us in the Entrance Hall when we returned to the castle.

"Did you find Professor Dawlish in the Greenhouse?" she asked.

"He was," Sherlock said. "The interview was most illuminating. You haven't been very forthcoming with us, Ms. Granger."

She gave an awkward smile. "Well, I don't want to prejudice your investigation."

"Professor Dawlish seems quite prejudiced himself. You don't find it an odd coincidence that the boy was murdered in his stepfather's classroom?"

Hermione gave a wary look around them, evidently concerned about eavesdroppers. An exodus of students were pouring onto the grounds.

"I'll answer any questions you have. But first, join me — the Quidditch match will be starting soon, and we shouldn't be late."

We joined a stream of students climbing a low hill up to the Quidditch pitch. It was oval-shaped and massively large — larger than several football fields put together. Along its circumference were towers for spectators, each rising perhaps a hundred feet into the air. It was a daunting climb for a hobbled old man such as myself. My bad leg was searing with pain by the time we reached the top and took our seats in a middle row.

Hermione noticed my discomfort.

"Allow me," she said. Before I could inquire what she meant, she produced a short ivywood wand. With it she tapped my leg, and muttered, "Episkey!"

In an instant, the pain quite thoroughly melted away. It was one of the most euphoric sensations I have ever experienced, the sudden expulsion of acute and debilitating pain. If I had any lingering doubt about the reality of magic, it now vanished.

"Oi, Hermione!"

We looked up to see a tall, freckled, red-haired man climbing the stairs towards us. He was grinning from ear to ear — though one of his ears was actually missing.

"George!" Professor Granger embraced him with a warm hug.

"Fancy seeing you here," he said. "Gosh, it's been ages. How are you and ol' Ronnie getting along?"

"Divorced. Erm… didn't Ron tell you?"

"He tells me many things, most of them are not worth hearing. I've developed an acute ability to tune out everything he says. Helps only having one ear. By the way, congrats on your appointment to Headmistress."

"A poisoned chalice," she said wryly. "There's a lot less academics and a lot more bureaucracy than I ever could have imagined. But it comes with certain perks. Free room and board, for a start."

George chuckled, and then he motioned to me and Sherlock. "Who are these two?"

"John Watson and Sherlock Holmes," Hermione said.

George shook hands with each of us in turn. " 'Ello mates. I'm George Weasley. Why the Muggle garb?"

"Because we're Muggles, apparently," I said sardonically.

George guffawed. "Muggles at Hogwarts! I'll say, Hermione, you really are making changes around here."

"I've brought them here to assist with the murder case. Sherlock is quite renowned in the Muggle world."

"Sherlock? Wait a sec — I've heard my dad mention you. You're Mycroft's brother — that famous Muggle detective!"

Sherlock did not deign to reply.

"What brings you here, George?" Hermione said, shifting the topic.

"Business is booming. Weasleys' Wizard Wheezes is seeking expansion — we'd like to buy out Zonko's in Hogsmeade. It'd put us closer to our target demo. But Zonko's is reluctant to sell."

"Shame."

"It really is. Did you know Zonko's uses artificial dung flavoring in their dungbombs? Wheezes only uses real dung. We never compromise on quality."

"I'm sure Filch will be delighted to hear about it."

George took his seat higher up in the stands, as the commentator began announcing the starting lineup of both teams. I watched in amazement as students mounted broomsticks — actual broomsticks — and took to the air, soaring with graceful agility despite the fierce buffeting winds.

"Quidditch," Hermione explained, "is the most popular sport in the Wizarding world. The goal is to score the most points."

She went on to describe the basic contours of the sport. There were four positions (Chaser, Beater, Keeper, and Seeker) and three types of balls (quaffle, bludger, and snitch). Chasers try to toss quaffles into hoops, which are guarded by Keepers. Each successful toss earns 10 points. Beaters knock bludgers at their opponents to keep them off balance, while Seekers race around the pitch, searching for the tiny golden snitch, whose capture nets 150 points and ends the game.

"Idiotic," said Sherlock.

"Why?"

"The game is hopelessly imbalanced. Presumably, before the snitch is caught, the point differential is typically within 150 points, so the Seeker is the only player who truly matters. The Beaters, Keepers, and Chasers are merely a sideshow."

"Well how would you change it?"

"Many sports have regulation time. Establish a time allotment and the snitch can be caught multiple times during regulation, each time worth 100 points instead of 150. Or, alternatively, catching the snitch merely ends the game, but awards no points."

Hermione pursed her lips, considering. "All good points. Honestly, I don't really enjoy Quidditch. But, being Headmistress…" She shrugged in a way that suggested she was obligated to attend.

The players were in midair, arrayed in starting formations. The referee — a willowy ginger who looked barely older than the students — gave whistle and the balls were released. The players began zooming around the pitch on their broomsticks so fast that they were a blur.

An older student was at the front of our stands holding a microphone. Her voice boomed across the pitch.

"Hello, good morning, and welcome, Hogwarts! Hufflepuff versus Slytherin is now underway! It's colder than a witch's tit so let's pray that Flint will swiftly catch the snitch and bring a premature end to this school-sponsored mandatory fun-time event."

"Stick to the game, Bethany!" Hermione called to her.

"Of course, Headmistress! Anyhoo, Marietta has possession of the Quaffle, and she's a mean flyer on her Nimbus Five-Thousand …"

As the game progressed, I turned to Hermione with a question that had been bugging me.

"What can you tell us about Dexter's parents?"

"His mother works for the Ministry," she said. Lowering her voice, she said, "as a spy. Very difficult to reach. The Ministry has had difficulty contacting her, they don't know where to direct the owls, and they're wary about blowing her cover. Dexter's father passed away recently."

"How recently?" Sherlock asked. "And why?"

"Few months ago. There was a … mishap in the Department of Mysteries. I don't know all the details, but he died as a result. He and Dexter's mom were — "

"Divorced, we know," Sherlock said.

Hermione smiled. "I know it's only been a day, but do you have any preliminary theories?"

"Less than a day," corrected Sherlock. "And I have seven."

Hermione looked askance at him, unsure if he was serious or not. "What's your leading theory?"

"Poison. Dexter may have been poisoned by a rival or enemy prior to entering the Greenhouse. I reckon wizards have a greater variety of poisons available to them."

Hermione nodded slowly. "It would not be difficult for a determined student to brew a fatal potion…"

"Dexter's body is being autopsied, right? Are they testing for poison?" I asked.

"They do a blood panel for common agents."

"Search for uncommon agents as well," Sherlock said officiously.

"There are innumerable poisons. It would require a lot of blood."

"He's dead. He won't need it."

Hermione sighed. "Well, I… I may be able to pull a few strings."

Meanwhile the Quidditch match, which I'd been barely paying attention to, was neck and neck. Despite the frigid cold, the Chasers of both teams were having ample success putting the Quaffle into the goalposts. Slytherin and Hufflepuff kept leapfrogging one another on the scoreboard.

"Applebee puts it through the hoops again! 90-80 advantage Hufflepuff!"

"And woah — look at that! Malfoy is going to town today on those bludgers. Merlin's beard! I've never seen a bludger move with such terrifying ferocity!"

Sherlock, oblivious to the Quidditch match, returned to the topic of poison.

"…of course," Sherlock muttered, "this is just one theory."

"Out of seven," Hermione said.

"Seven so far. Does the greenhouse have a retractable roof?"

"It does actually, yes. In the summer months, Dawlish likes to open the roof… He says the fresh air is beneficial to the plants."

"Then an eighth theory presents itself — brooms could have been used for ingress and egress. It would have required planning and preparation. And knowledge, presumably, about how to retract the roof."

"Again, I reckon only a Professor would be able to do that… It would involve very complex magic."

"Perhaps. Dawlish told us that there was a vendetta between Dexter Zabini and Scorpius Malfoy."

"A one-sided vendetta. Dexter had no hate in his heart for Malfoy. He was just a Prefect doing his job."

"But Malfoy despised Dexter, and had a motive for murder."

"His alibi —"

"— is irrelevant, if poison was the murder weapon. It could have been administered days prior to his death."

"You don't understand. With his consent, and with Ministry officials as witness, Scorpius was placed under Veritaserum. It's a powerful truth serum. Under its influence he assured us in no uncertain terms that he had no involvement in Dexter's death. None whatsoever, not even indirectly."

"Perhaps he used magic to overcome the effects of Veritaserum," Sherlock mused.

Hermione scoffed. "It doesn't work that way. There are no known antidotes to Veritaserum. Forgive my immodesty, but even I could not beat it."

"Show me the interrogation."

Hermione recoiled. "What? How?"

"The same way you showed me the crime scene. Your Pensieve."

"Ah, yes, very well." She sighed. "I'll tell you what, meet me tomorrow after breakfast at my office, and I will show you my recollection of our interview with Malfoy. Is that fair?"

Before Sherlock could reply, a loud gasp from the audience drew their attention.

"Look at that!" Beth, the announcer, exhorted spectators. "Malfoy wallops the bludger right at his own teammate. Flint is hanging on for dear life, and —"

Just as Beth said that, Flint lost her grip on her broom and began plummeting to earth. Hermione leapt from her seat and shouted "Arresto Momentum!" A bolus of pure white light descending onto the field. It slowed Flint's descent, but it was not enough. Flint crashed hard on the turf below.

"And — she — is — DEAD!" Beth roared. "Brilliant gambit by team Slytherin, killing one of their own teammates. They've capitalized on the commotion by scoring two more goals, as Hufflepuff Keeper Tristan Macmillan stares in shock!"

The referee blew his whistle belatedly, stopping the game, and he and other faculty raced to Flint's aid. The girl lay motionless on the Quidditch pitch.

"Oh, heavens," I said. "They're lifting her head — if she suffered a spine injury that could induce paralysis."

"Olivia Flint will be taken to the Hospital Wing," Hermione said, a bit frazzled, "where I assure you she will receive the best possible care."

"I'd like to see her."

"I don't—"

"I'm a doctor. Please, I insist."

Hermione threw up her hands, a bit annoyed. "Very well."

I didn't know it at the time, but what had happened that afternoon on the Quidditch pitch that windswept December afternoon was intimately connected with events soon to follow – and with the mystery of Dexter Zabini.