At midnight, everyone in the dormitory was asleep.
Fred quietly pulled back his sheet, got out of bed, walked to George's bed, and gently pushed him twice, making a shushing motion.
George slowly got up, put his robes back on, picked up his wand, and tiptoed out of the room, with Fred softly closing the door behind him.
The two walked up the spiral staircase and entered the Gryffindor common room.
The room was empty, and the fire in the fireplace had burned out. Instead of leaving immediately, they found an armchair and sat down.
Fred pulled out the old parchment from his robe pocket, tapped it lightly with his wand, and said, "I solemnly swear that I am up to no good."
"Me too," George muttered, bringing his lit wand closer to illuminate the Marauder's Map for Fred.
As the castle map unfolded, Fred spread it across the table, and the two began to search for Filch's name. The annoying caretaker was resting in a bedroom next to his office on the first floor, while his cat, Madam Norris, prowled the fifth floor.
Peeves, the mischievous poltergeist, was in the History of Magic classroom on the second floor, and Dumbledore was pacing back and forth in his office.
"Where's Percy?" George whispered.
Fred pointed to Percy's dormitory. "Sleeping."
"Okay, the night excursion begins!" Fred and George high-fived, put away the Marauder's Map, and prepared to set off.
But as soon as they climbed through the portrait passage, the Fat Lady spotted them. "Where are you going at this hour?"
"Night excursion, Madam," Fred said with a grin.
The Fat Lady was stunned, never imagining someone would admit to such a thing so boldly.
"Let's go!" George pushed Fred forward, and the two quickly disappeared around the corner of the corridor.
Standing in the dark, silent hallway, the twins' spirits soared. With the Marauder's Map in hand, the entire Hogwarts castle was theirs to explore.
As for Filch, he would never be able to catch them.
"Albert will definitely regret not coming with us," Fred said happily after reconfirming Filch's location.
"I think Albert wants to wait until he masters the Disillusionment Charm before joining us," George replied, his tone full of excitement. "But this is our first time using the Marauder's Map; using it alone is good enough."
In truth, the twins were reluctant to share the secret of the map with too many people.
"Once we figure out all the secret passages in the castle, we'll surprise those two," Fred said gleefully.
During the day, there were passages they couldn't openly try, but at night, with no one around, they had no such concerns. This was the perfect opportunity.
Fred led the way, map in hand. The corridor was pitch black and eerie, and with every turn, his heart pounded faster.
It was exhilarating.
"Stop!" Fred quickly extinguished his wand and shushed George.
"What's wrong?"
"It's Nearly Headless Nick."
After waiting thirty seconds, Fred, under George's cover, re-lit his wand to check the ghost's location.
"He's gone far!" Fred said.
The two tiptoed down the stairs and stopped in front of a knight's armor statue on the seventh floor.
On the Marauder's Map, an ink dot marked "Fred" tapped the visor of the knight's helmet with his wand, and a spell appeared beside it: Mouth to Door.
The two exchanged glances.
"Let me try. Mouth to Door." George extinguished his light, tapped the visor with his wand, and the statue bent down. Its visor widened like a mouth opening, large enough for a thin person to enter.
Fred checked the map, confirmed no one was nearby, and quickly stepped inside, George following close behind.
The passage was narrow, the ground thick with dust and cobwebs.
"I bet this path hasn't been used in ages." Fred pushed aside cobwebs with his wand, struggling forward. The path sloped downward, ending at a stone door. When they passed through, they found themselves blocked by a wooden door.
"Where are we?" George asked.
"Fourth floor. I remember this place. Some doors, after opening, have another stone door inside that can't be opened."
"I bet this is a one-way passage," George said, pushing the stone door.
At Hogwarts, some doors weren't real at all, but solid walls disguised as doors. Now it seemed these were secret passage doors too—only passable from the other side.
George carefully left the wooden door ajar. Just as he raised his wand, a nearby portrait of a man in pajamas and a nightcap complained, "Watch it, kid, we're trying to sleep."
"Oh, sorry!" George lowered his wand and said to Fred, "Let's get out of here first."
"This way, I know another passage!" Fred led them to a vase at a corner on the third floor.
George tapped the vase twice with his wand, saying, "Turn left, turn right."
The vase made a grinding sound, and a black spot appeared in a landscape painting on the adjacent wall. The spot grew until it became a door. George grabbed the knob and pushed gently. The frame swung open, revealing a hidden entrance.
Inside, they discovered a passage leading outside the castle. The exit was on the mountain path to the boathouse, concealed by weeds. No one would ever suspect a door was there.
As they stepped out, the mountain wall sealed itself again.
"Who would have known there was an entrance here?" Fred tapped the rock. It was solid, impossible to imagine a door hidden within.
"How do we get back in? Don't tell me we'll stand here in the wind all night." George hugged himself, shivering.
"Let me see." Fred checked the map, which showed the instructions clearly.
"Tap the raised stone three times," he muttered, finding the spot. "Open Sesame."
The stone wall shifted, slowly opening to reveal the hidden passage once more.
The two quickly squeezed inside. The night wind had been bitterly cold, and George sneezed several times on the way back.
"Are you alright?" Fred asked.
"I think I've caught a bit of a cold," George said, rubbing his nose.
"Let's call it a night. We have classes tomorrow," Fred said, stifling a yawn.
George agreed.