Harry Potter followed Professor McGonagall to the area between the first floor and the basement.
When he realized they were headed for the bathroom where he, Ron, and Hermione had secretly brewed the Polyjuice Potion, a look of dread spread across his face. At that moment, he was certain their theft of Snape's ingredients and the brewing of a forbidden potion had been discovered.
"Professor McGonagall..." he stammered.
"Why are you stopping?" she said, her voice urgent. "Headmaster Dumbledore is waiting for you!"
Her impatience only made Harry more nervous—he thought she was furious.
The moment he heard Dumbledore's name, his legs nearly gave out.
Was Professor Dumbledore angry? Was he about to be expelled? It was over... In ten minutes, he'd be packing his things. What would the Dursleys say when he showed up on their doorstep?
But as soon as he stepped into the bathroom, he froze.
Inside stood Professor Dumbledore—not alone, but joined by Professors Flitwick, Sprout... and even Snape.
The door to the stall where they had hidden the cauldron and leftover materials was still shut. It didn't look like anyone had found it.
"Good afternoon, Harry," Professor Dumbledore said kindly. "We need your help with something."
"Help?" Harry exhaled in relief. Judging by Dumbledore's expression, this wasn't about the Polyjuice Potion. He wasn't being expelled.
"Come here," Dumbledore said, giving his shoulder a reassuring pat. "No need to be nervous."
Harry nodded and leaned down as instructed.
Bang! The bathroom door flew open.
Two second-year students rushed in.
"Miss Granger, Mr. Weasley!" Professor McGonagall frowned.
Harry's face paled, and he desperately signaled to Hermione.
But Hermione hadn't noticed. Her eyes had been locked on McGonagall and Dumbledore the moment she entered.
"Professor McGonagall, Harry didn't do anything—it was me!" she blurted, words tumbling out like a waterfall. "It was my idea to borrow the Polyjuice Potion book from the restricted section. I threw the Dungbombs in Potions class two months ago. I stole the Bicorn horn and Boomslang skin from Professor Snape! If you're going to punish someone, punish me. Harry and Ron had nothing to do with it!"
Hermione's thinking was simple: Harry and Ron had already received a serious warning at the start of term. If they got in trouble again, they could be expelled. She had to take the fall. At least Professor McGonagall liked her—she might go easy.
Ron was panting beside her, but it was too late to stop her.
The room fell into an awkward silence.
Professor McGonagall's face darkened with rage.
Professors Flitwick and Sprout exchanged glances.
Snape stood there frozen for a few seconds before reacting.
"Well done... Granger..." he sneered. "Now I know."
Hermione's stomach dropped. Seeing Harry's despair and the other professors' reactions, she realized she had misunderstood everything.
"What's going on?" A clueless voice interrupted the tension.
The Defense Against the Dark Arts teacher had arrived. Gilderoy Lockhart stepped in, looked around the crowded washroom, and said, "I thought this was an abandoned girls' bathroom..."
"Oh, Headmaster Dumbledore! Merlin's beard, you're back!" Lockhart exclaimed.
"Good afternoon, Gilderoy," Dumbledore greeted him with a smile. "We've just located Slytherin's Chamber of Secrets. Would you care to join us?"
"Slytherin's Chamber of Secrets...?" Lockhart's face flickered, but he quickly forced a grin. "Why, of course! In fact, I've long suspected this bathroom was the entrance! I just haven't gotten around to taking care of it…"
Dumbledore ignored him and turned to Snape. "Severus, perhaps this isn't the time to dwell on minor matters."
"Minor matters?" Snape sneered. "Very well, if you say so, Dumbledore."
"Of course, only relatively speaking," Dumbledore replied with a serious tone. He turned to Hermione. "Miss Granger, I'd like you to stop by my office this evening. We'll have some Prince of Wales tea. My office is on the top floor, past the spiral staircase and in front of the stone gargoyle. The password is 'lemon ice cream.'"
"Yes, Professor," Hermione replied nervously.
"Now, back to the matter at hand," Snape said coldly. "Potter, over here... Do you see the side of this copper tap shaped like a dragon? There's a tiny snake carved into it... Speak to it. In Parseltongue."
...
A bright white light flashed from the serpent-shaped tap, and it began to spin rapidly.
Moments later, the entire sink started to shift. They watched as it vanished, revealing a wide pipe—large enough for someone to slide through.
"Amazing!" Lockhart exclaimed, but when he saw his colleagues' disapproving looks, he quickly composed himself.
"It seems only one person can go down at a time," Dumbledore said, smiling. "Gilderoy, as our Defense Against the Dark Arts teacher, surely you've always wanted to defeat Slytherin's monster. Here's your chance."
Lockhart gaped, speechless. He opened his mouth, but no words came out.
Snape gave him a small push with his foot—Lockhart screamed and tumbled down the pipe.
The rest of the teachers looked away, pretending not to see anything.
Harry was about to follow when Snape held him back, gave him a cold glance, and then slid down second.
One after another, the teachers and students climbed into the pipe...
Professor McGonagall tried to send Ron and Hermione back to Gryffindor Tower, but Professor Dumbledore stopped her. He agreed to let the two second-years join the "mission."
It felt like plummeting down a slimy, endless, twisting chute in complete darkness. The tunnel twisted sharply as it descended into darkness.
After several minutes, they landed one by one with a splash on damp stone.
They found themselves in a dark, stone passage—tall and wide enough for several people to walk upright.
They must have descended miles beneath the castle.