The sound made Harry's blood run cold.
He suddenly opened his eyes. The scar on his forehead began to throb.
"We have to go!" Harry grabbed Ron and Hermione by the arms and dragged them in the opposite direction.
"Harry, have you gone mad?" Ron stumbled as Harry pulled him along, nearly falling over.
"What's going on?" Hermione was just as baffled by the sudden change.
Harry dragged them to a corner before stopping. All three were panting.
"I just heard someone talking," Harry said in a low voice, his green eyes full of tension.
"He was talking about the Philosopher's Stone. He said he had to get it."
Ron's blue eyes widened.
"What? I didn't hear anything, Harry. It was quiet back there."
"I'm sure I heard it!" Harry insisted, his hand unconsciously moving to the scar on his forehead.
"That voice... It was hoarse and evil."
Hermione studied Harry, a thoughtful glint in her brown eyes.
"Harry, are you sure you didn't imagine it?" she asked cautiously.
"I mean, exams are stressful. Sometimes people hear things that aren't there..."
"I didn't imagine it!" Harry cut her off, his voice growing impatient.
"I'm sure I heard that voice!"
Hermione fell silent for a moment, then slowly nodded.
"Actually... there are sounds that only people with certain abilities can hear. I read about it in a book," she said thoughtfully.
Ron's face turned pale. "Who could it be? Who would want the Philosopher's Stone?"
Harry's expression grew serious.
"It must be Voldemort."
At the name, Ron shuddered, his bright red hair standing on end.
"Don't say that name," he stammered.
"Wasn't Voldemort driven away by Charlie? He shouldn't be at Hogwarts anymore."
"Do you remember what Dumbledore said?" Harry's voice grew heavy.
"He said Voldemort would return. As long as