The three were startled by Nick's sudden, piercing scream.
"Run!" Harry was the first to react, shouting loudly.
The next moment, the three raced frantically down the corridor. Hermione, frightened by the unexpected terror, couldn't help but scream as well.
They didn't know what had happened, but Nick's sudden scream made them feel there was some unknown danger lurking around them, especially given that the school was already unsafe.
They ran at full speed for about fifteen minutes before finally stopping.
Huff, huff...
The three were gasping desperately for breath, their faces flushed bright red. They simply couldn't run anymore.
"What... what just happened?" Ron gulped air frantically, feeling like his lungs were about to burst.
"I... don't know," Harry shook his head, completely out of breath.
Hermione was utterly unable to speak.
Even so, they all vigilantly watched their surroundings, guarding against any dangerous things that might suddenly approach.
After about a minute, the three finally caught their breath.
"Did Nick... discover something? That yellow light?" Hermione speculated.
"Possibly, but how did he discover it?" Harry was somewhat puzzled.
When they were fleeing, Harry had specifically looked around but hadn't noticed anything unusual.
Of course, it was also possible that because he was running too fast, he had missed some crucial information.
"Do ghosts have strong perception abilities? I didn't know that," Ron said with confusion.
"And Nick didn't even warn us before running away. Really, he's already a ghost but still so afraid of death. Can he die again?"
Ron couldn't help complaining about the situation.
"Maybe ghosts have their own things to fear," Harry said helplessly.
"Regardless, Nick's scream did remind us to run quickly, so it was another kind of warning," Hermione concluded reasonably.
Ron didn't say anything more. He had just been venting casually and didn't really blame Nearly Headless Nick.
"What do we do now? Hide here, or go back to Gryffindor Tower?" Ron asked.
They were now hiding in an abandoned classroom. Due to running too fast earlier, they hadn't looked at their surroundings and didn't even know exactly where they were.
Harry pondered for a moment and said, "Let's not go out yet. There might be danger in the castle. Let's wait for Dudley here."
This was the safest approach, much better than wandering around outside.
"But can Dudley find us?" Hermione asked somewhat uncertainly.
"He can find us," Harry said with complete certainty.
Although he didn't know what methods or magic Dudley had, Dudley always managed to find them at crucial moments.
Like when they had driven the car to school, Dudley had told them afterward that he had discovered them flying in the sky, so he hadn't been too worried about their situation.
"Alright, let's wait here for a while. At least with Dudley around, I feel much safer," Ron said, sitting down against the wall.
Just as he finished speaking, light footsteps could be heard from the corridor outside.
"That sounds like Dudley!" Harry's expression changed as he recognised what sounded like Dudley's familiar footsteps.
He quickly opened the classroom door and peeked out, indeed seeing Dudley approaching.
"Harry, how did you end up here?" Seeing Harry, Dudley quickly walked over with obvious concern.
"We might have encountered the hidden danger just now," Ron hurried out to explain the situation.
"Danger?" Dudley frowned. He hadn't sensed any danger at all.
"When I went back to look for you earlier, I heard a scream from downstairs. I immediately ran over but didn't see you anywhere."
"It was Nearly Headless Nick. He was talking to us, then suddenly screamed and ran away. We felt there might be some danger around, so we ran away too," Hermione explained.
"That Gryffindor ghost?" Dudley's expression shifted with understanding.
"Yes, he didn't say anything. Just plunged headfirst into the wall and escaped. We were startled too," Harry said.
Hearing the three's description, Dudley suddenly realised something and looked down at the golden ring on his index finger.
"I think I know why he ran away," Dudley said.
"What?" the three asked in unison with confusion.
"Let's go. There's no danger in the castle right now," Dudley said to the three.
Nearly Headless Nick had probably been frightened by the Solar Halo of the Solar Ring.
Dudley had been wearing the Solar Ring while patrolling recently, with the purpose of being able to use the Solar Ring's ability to dispel that powerful dark magic immediately if he encountered the petrification situation from before.
But the Solar Halo's effect would work on all wraiths and ghost-like entities. Just now, it was probably because Dudley approached Harry and the others while wearing the Solar Ring, causing Nearly Headless Nick to feel the burning of the Solar Halo, which made him flee in panic.
Dudley briefly explained to the three and led them toward Gryffindor Tower.
The next day, when Dudley and the others were having breakfast in the Great Hall, they saw Nearly Headless Nick again.
"Last night..." Harry took the initiative to ask.
"Oh! I'm so sorry about last night. I hope I didn't frighten you," Nearly Headless Nick said apologetically.
"I suddenly felt my body getting hot, as if my whole person... no, my whole ghost was about to burst into flames, so I fled immediately."
"I really don't know what happened."
"I need to tell the other ghosts that the danger existing in the castle might threaten ghosts too."
"How terrifying."
Nearly Headless Nick said with obvious worry.
Harry, Ron, and Hermione exchanged meaningful glances, then looked at Dudley, before silently lowering their heads to eat.
Dudley's mouth twitched slightly. After composing himself, he said, "Well... that's really unfortunate. I hope this doesn't affect you all, Sir Nicholas."
"I hope so."
Hearing Dudley call him by his proper name, Nick smiled and nodded.
"But this matter must be taken seriously. I need to let all the ghosts know about the danger of this situation."
"Oh right, Halloween is my five-hundredth deathday. I can inform everyone about this then. Also, may I invite you to attend my deathday party?"
Nick looked at them hopefully.
Dudley and the others exchanged glances, all feeling somewhat guilty about the real situation.
"Well, yes, we're honoured to be invited," Dudley finally said.
"Oh, my dear children, it's wonderful that you can come."
Nick appeared extremely excited, praising them for quite a while before leaving satisfied.