"P-P-P-P-Professor Cavendish..."
George and Fred were now thoroughly on edge.
Neither of them knew why the newly appointed professor, Sherlock, would show up here.
Of course, merely appearing wasn't the point; the point was that, one minute earlier, they had used their secret treasure—the Marauder's Map—right in front of the new Defence Against the Dark Arts professor.
Once he realized what had happened, George hastily hid the Map behind his back.
The next second, he and Fred shared a sheepish grin in perfect sync.
"Fancy meeting you here, Professor Cavendish. Out for a late stroll? We just stepped out and—bump—there you were."
"Yeah, it's awfully late. You should turn in soon; we're heading to bed ourselves. Staying up stunts your growth."
Talking over each other, George and Fred tried to laugh the whole Map incident off while shuffling toward the entrance to the Gryffindor common room.
Naturally, their painfully obvious cover-up wouldn't fool Sherlock.
The instant they turned, he seized the backs of both their collars.
Fred and George froze.
Gulping, they exchanged furtive glances: tonight wasn't going to end so easily.
"Uh… is there anything else, Professor Cavendish? We really need to get to bed—Mum says late nights are bad for us."
George attempted one last stand.
Sherlock merely stretched out his hand and said calmly, "Hand it over."
Knowing further resistance was hopeless, the twins pulled long faces and reluctantly produced the hidden Map.
They wouldn't dare try any tricks in front of Sherlock.
Over the summer, Mrs. Weasley had told them countless times how formidable their professor had been as a student.
After graduation, he'd served as an Auror for more than a year, then quit the Ministry out of boredom and devoted himself to magical research.
In less than two years, he'd produced two books on defensive spells praised by leading curse-masters.
At barely twenty, he'd been appointed to teach a core subject at Hogwarts—a feat few could match.
So they felt safe pranking Filch; after three years of mutual antagonism, they'd long since deduced he was a Squib.
Sherlock, however, clearly wouldn't be so easy to fool—at least on the surface.
Taking the parchment from the twins, Sherlock noted the spell still active and immediately grasped its purpose.
It was a magical map of every nook and cranny of Hogwarts.
Beyond the castle, every building and scrap of ground within the school grounds appeared on it.
Most remarkably, it showed the real-time positions of everyone on the premises.
For instance, he could see Dumbledore pacing in his office, Filch racing toward his quarters, and Professor Flitwick chatting with Astronomy Professor Sinistra in the staffroom.
With this map, the entire school lay open to him—exactly what he needed right now.
He looked up from the parchment.
His gaze, heavy with authority, fixed on the twins.
"Very well, let's discuss how to settle tonight's affairs, Mr. Weasley and Mr. Weasley."
George and Fred stood meekly.
They knew "discuss" meant they had no say; all they could do was pray he wouldn't confiscate the Map permanently or tell their mother.
"You set a trap that left Mr. Filch in a state, tried sneaking out after curfew, and carried a prohibited map of the school—any one of these is a serious breach of rules."
Halfway through, they were convinced he would march them straight to Professor McGonagall—until his tone suddenly shifted.
"Still, your parents and I are on good terms, and learning their sons pulled such stunts would upset them. So I'm willing to be lenient."
Hope flashed across their faces.
"I can keep quiet about your rule-breaking and even let you keep the Map—but to teach you a lesson, I'll hold on to it for now. If your first-term performance satisfies me, I'll return it at Christmas."
Reassured they'd get it back, they hastily vowed to behave.
"We swear we'll be model students for the next few months, Professor Cavendish!"
"Let's hope so."
They dared not push further; having the Map returned at all already felt like a windfall.
Besides, they'd only promised to behave "for the next few months"; once the Map was back, all bets were off.
Cautiously, they asked, "May we go to bed now, Professor?"
Sherlock held the Map out.
"Deactivate it."
Fred took the parchment, raised his wand, and recited the spell in front of Sherlock.
"Mischief managed."
The moment his wand touched the parchment, every line shrank to a single ink blot and vanished; the Map reverted to ordinary parchment.
Having memorized both the opening and closing incantations, Sherlock reclaimed the sheet and nodded them toward the dormitory.
The twins turned to the Fat Lady's portrait, gave the password, and ended their aborted nighttime excursion.
Only Sherlock remained in the silent corridor.
He tapped the now-plain parchment with his wand.
"I solemnly swear that I am up to no good."
Ink lines blossomed outward like serpents, weaving into a real-time plan of Hogwarts.
Surveying tonight's unexpected prize, Sherlock's lips curved in a satisfied smile.