Hermione poked her head around the corner and sighed. "Harry, stop investigating the killer dog and come down to lunch."

Harry had turned the space around the door to the third-floor corridor into a makeshift lab. A table he'd stolen from the library groaned under the weight of test tubes, computer monitors, and machines that went bing!, while several microphones and cameras were aimed at the door, recording data.

"Science trumps lunch, Hermione," Harry replied, tapping an oscilloscope to make sure it was working. "Those wave patterns don't look good. I'd say Chopper's got a nasty case of worms."

"Harry, I like a good mystery as much as the next 11-year-old plucky witch, but I feel like you're taking this too far."

"Nonsense," Harry said. A muffled sneeze shook the door behind him. "Oh, I need to add that to the activity log." He picked up a tape recorder. "12:33: subject sneezed. Registered 3.1 on the Richter scale. Possible dust allergy; needs further research. Will collect snot for analysis. Hermione, can you give me a hand?"

"Oh, sorry, Harry, I have charms to do," the girl replied, backing away slowly. "Maybe next time."

"Ok, I'll call you when I need to collect a stool sample."

"Please don't."

"Headmaster, we need to talk about Harry,"

"Ah, yes, Mr. Potter-Sanchez. How is he doing in your class, Severus?"

"The little bastard is quite the natural at potions," the Slytherin head of house replied grudgingly. "Although he keeps referring to it as 'chemistry', which I'm sure he does just to spite me."

"Ah, the youth of today. Such insouciance is quite refreshing."

"I must report that Potter and his nephew Smith have taken an unhealthy interest in the third-floor corridor, despite your warning at the start of term."

"Oh, dear, how unexpected," Dumbledore said, smiling.

"Mr. Filch has tried on several occasions to chase him away, but Sanchez ignores him, or at best replies 'Fuck the Police', whatever that means."

"Let the young man sate his curiosity," the Headmaster replied. "So long as no harm comes from it."

Harry took off for the grand staircase like a track star, sliding around the corner so hard he left skid marks. "Run for your lives!" he screamed, barreling through a group of confused third years.

A moment later, a pissed-off looking cerberus slid around the corner, crashing into a suit of armor. The third years decided to follow Harry's advice.

Hermione, Ron and Morty were coming out of the great hall when Harry appeared, sliding down the banister and somersaulting into a heap before them. "Guys, I made a horrible mistake."

A loud roar quickly clued them in. "Harry, what did you do?" Ron asked.

"I may have tried to take its temperature," Harry said.

"Orally?" Morty asked.

Another roar. "Guess again."

There was a crash as the giant dog dropped three stories, cracking the floor beneath it as it landed. Upon locking eyes with Harry, it's three mouths bared their fangs.

"Don't make any sudden moves," Harry whispered, frozen in place. "It responds only to movement."

"Those are T-Rexes, Harry," Morty said.

"I know, I'm just hoping it applies to mythical dog beasts, too."

"Oh, for Merlin's sake. Hermione stepped forward and waved her wand. A large beach ball popped into existence two feet from the cerberus's nose. "Does doggy want the ball?" Hermione asked, waving her wand back and forth, the ball echoing her movements.

The cerberus dropped its heads to the floor. It's wagging tail caught a seventh-year Ravenclaw in the stomach and sent her flying through a stained glass window.

"Go get it!" Hermione shouted, tossing the ball through the open door. The cerberus enthusiastically took off after it, barking happily.

"I cannot believe you four," McGonagall stormed back in forth across her office floor. "Tangling with a fully-grown Cerberus and endangering the lives of yourselves and everyone in the castle. You could have been killed!"

"But we weren't," Harry pointed out.

"You put twelve students in the infirmary."

"They'll live."

"The poor Ravenclaw is paralyzed."

"Well, that's your problem, as this school clearly does not follow ADA specifications."

The deputy headmistress waved her wand, and Harry suddenly found himself transfigured into a donkey. "I am deeply ashamed of you all."

"Are you going to expel us?" Hermione asked, shaking.

"That would be too fitting a punishment," McGonagall snarled. "Ten thousand points from Gryffindor, and you all have detention with Filch for a month."

The door to McGonagall's office swung open. "Ah, Minerva, I see you are administering punishment to Sanchez and friends," Dumbledore said, casting his eye over the Gryffindors. "I must say, Granger, your handling of a fully-grown cerberus was quite impressive. Eleven thousand points to Gryffindor."

"Albus!"

"Oh, right, sorry Minnie." Dumbledore put on a mocking frown. "Don't do it again. On a side note, Filch will be busy repairing the third-floor corridor, so I'm afraid you'll be spending your detentions in the kitchen, as chocolate cake taste testers. Ta!" Dumbledore waved before closing the door, narrowly missing a houseplant hurled by McGonagall, who had begun to foam at the mouth.

"I guess we'll take our leave, then," Morty said, grabbing Jackass-Harry by the reins. "C'mon, better get down to the kitchens. Those chocolate cakes aren't going to taste themselves!"

"So, Hagrid, have you caught the Cerberus yet?"

Hagrid smiled. "Oh, aye. Fluffy's a gentle creature at heart. 'E's been taken to be fixed. Should make him less aggressive."

Harry snapped his fingers. It was a rather difficult gesture for him to pull off, as McGonagall's spell had yet to wear off, and he was still a donkey. "Wait! Fluffy?"

"Aye, that's the name I gave 'im," Hagrid replied.

"So you put the Cerberus in the castle?" Ron asked.

"Aye, Headmaster's orders." Hagrid's eyes widened. "Oh, no."

"So you know what it was guarding!" Hermione said.

Hagrid's eyes widened. "Well, uh, no, no, I know nothin' about that. I just collected it from Gringotts and got Fluffy to guard it, I have no idea what yer talking about!"

"What about Gringotts?" Harry asked.

"Does it have something to do with the break-in they had the day before school began?" Ron asked.

"I can't speak for Dumbledore and Nicholas Flamel," Hagrid replied. He clapped a hand over his mouth.

"Who's Nicholas Flamel?" Morty asked, but it was too late. Before anyone could stop him, Hagrid had grabbed a pot hanging over the fireplace and beat himself into unconsciousness.

"More questions than answers," Harry said, scratching his chin with his hoof as they left Hagrid's hut.

"You're right, Harry," Hermione said. "Something is being guarded at Hogwarts, but what? It belongs to Nicholas Flamel, but who is he, and why is he important? Someone tried to steal it from Gringotts, but who and why?"

"All excellent questions conveniently conveyed verbally for an audience's benefit," Harry replied.