Perhaps because they had learned that Justin was still alive, or perhaps because the students trusted Dumbledore, the Castle remained calm.
The day after Halloween, apart from wild theories exchanged over meals about who the culprit might be, life continued without major upheaval.
But once students began investigating the words Argus Filch had scrubbed from the walls, rumors of the Chamber started to circulate throughout Hogwarts.
Even in Sherlock's class, pupils asked him about the legend of Slytherin's Chamber.
"This isn't a topic for my classroom. If you're curious, ask Professor Binns in History of Magic; he's taught here for centuries and knows far more than I."
Sherlock rapped on the blackboard, steering the lesson back on track.
"All right, pursue the Chamber in your own time. Right now, we need to focus on scoring top marks in this year's O.W.L.s."
"Memorize the three danger signs of a werewolf, and note that past papers love to ask which spell lets you escape a pursuing werewolf the fastest…"
The student attack and the supposed opening of the Chamber didn't upend Sherlock's life at Hogwarts; they only lengthened his library hours.
He knew the plot had veered off course, yet he had no way to steer it back.
All he could do was raise his magical level as fast as possible—at minimum, regain the Original Owner's strength before term ended.
While Sherlock was teaching fifth-year Defence Against the Dark Arts…
…in a second-year History of Magic class, Hermione publicly coaxed the full Chamber legend out of Professor Binns.
The obstinate Binns insisted the tale was mere fiction.
He treated it as a story; the students thought otherwise.
After all, Justin had been attacked only yesterday, and someone had scrawled across the wall that the Chamber was open.
Justin, the message claimed, was merely the first of the "unworthy" to be purged.
After class, Harry, Ron, and Hermione gathered.
"The Heir of Slytherin has to be in Slytherin House—who do you reckon it is?"
Ron posed the question, then answered it himself with conviction.
"It's Malfoy! He looked delighted after Justin was attacked, and his family has always spouted pure-blood nonsense—he could easily be Slytherin's heir."
Hermione weighed the possibility.
Ron's case was solid; with the scarce clues—and their own bias—Malfoy appeared the prime suspect.
Harry, however, wasn't listening.
He stared blankly into space, replaying the last Defence class before Halloween: when he had gone to hand in his homework, Justin had stood right in front of him, chatting with Professor Cavendish.
Ron and Hermione exchanged glances; both noticed Harry's distraction.
"What's on your mind, Harry?" Hermione asked suspiciously. "Do you know something we don't?"
Harry opened his mouth, uncertain whether to speak.
He hated to tarnish the reputation of the well-liked Professor Cavendish; he couldn't imagine him being the fabled Heir.
Yet, recalling that he himself had wished Justin a happy Halloween, he wondered if it was too great a coincidence that the attack followed the very next day.
Ron caught Harry's hesitation and scowled. "Why hide things? We kept quiet about that weird voice you heard."
Harry realized he shouldn't keep secrets from them and told them what he had been thinking.
When he finished, Ron's eyes bulged.
"So what—you suspect Professor Cavendish is the culprit? Have you lost it?"
Hermione stared at Harry, puzzled. "It's just a coincidence, Harry. Professor Cavendish simply wished Justin a happy Halloween in front of you; other teachers probably did too. We can't treat that as evidence or start suspecting a professor."
Ron added, "Besides, Professor Cavendish is a half-blood."
Harry and Hermione turned to him, silently asking how he knew.
"I heard it from George and Fred," Ron explained.
"Early in the term, they had something confiscated by Professor Cavendish, so they wrote to Charlie, asking about the professor's school days to see if he keeps his word."
"Charlie wasn't in the same year or house, but the professor was famous—apparently love letters filled a cauldron every year!"
Ron looked envious; Hermione cut in impatiently.
"We're not here to count love letters—though he's still popular with the girls."
"Charlie said everyone knows Professor Cavendish is a half-blood: his witch mother died when he was small; his father's a Muggle duke."
Hermione and Harry exchanged glances; both had lived in the Muggle world long enough to know what a British dukedom meant.
"Professor Cavendish is the son of a duke!"
They didn't dwell on it; a Muggle title hardly mattered to wizards.
Knowing he was a half-blood virtually cleared him of suspicion.
Harry scratched his head. "I never really suspected him; it just felt too coincidental."
Ron and Hermione saw no great coincidence—Malfoy remained the likelier culprit.
They continued debating ways to test whether Malfoy truly was the Heir.
Until Hermione came up with what they decided was a brilliant idea.