Luigi's brother was gone, and the dark inside the mansion swallowed everything. One minute Mario had been beside him on the rotted porch. The next, something dragged him through the front door, and the door slammed shut. Now Luigi stood inside the old house, hands out, seeing nothing. He had come here to save Mario. Instead he could not even see his own boots. He took one step. His foot found a hole in the floor. He fell to his knees, heart pounding. Somewhere ahead, wood creaked. Whatever took Mario was still moving in the black. Luigi could walk right into it and never know until claws found his throat. He patted his pockets. No matches. No lantern. Then he remembered the small green friend who had followed him up the hill. "Yoshi," Luigi whispered. "Are you here?" A soft chirp answered from near his elbow. Yoshi pressed against his leg, warm and shaking. The little dinosaur had never liked the dark, but he had refused to wait outside. Luigi felt the leather saddle on Yoshi's back. He remembered something. Yoshi could sniff out anything, even in pitch black. "Find Mario," Luigi said. "His smell. Find him, boy." Yoshi sniffed the floor. He chirped twice and tugged Luigi's sleeve, pulling him forward. Luigi crawled behind him, one hand on the saddle, the other testing the floor for holes. Step by step, Yoshi led him around a broken chair and past a cold fireplace. The blind walk became a trail. Luigi was not stumbling anymore. He was following. Then Yoshi stopped. He growled low. Ahead, two red points opened in the dark, like coals waking up. They floated at the height of a small child. A shadow took shape around them, black on black, its edges ragged and shifting. It made no sound. The red eyes fixed on Luigi. Luigi froze. This was the thing. Not the one that grabbed Mario, but something smaller, watching. It drifted closer, and the air went colder. Luigi grabbed a fallen board from the floor and swung it hard. The board passed through the shadow and cracked against the wall. The creature did not flinch. The red eyes brightened. Then the shadow turned and slid away down a hall, fast, like smoke pulled by wind. Yoshi barked and yanked Luigi after it. Luigi understood. The thing was not attacking. It was leading them somewhere. They chased the two red lights through the dark. At the end of the hall, a door hung open, glowing faint green from within. The shadow slipped inside and vanished. Luigi stopped at the doorway, breathing hard. He could see now. The blind dark was behind him. But what waited in that green light made him wish he was blind again. On the floor of the room lay Mario's red cap, empty, and a wet trail leading deeper into the house.

Luigi picked up Mario's red cap and pushed it into his pocket. The green doorway glowed at the far side of the room. But when he reached it, the door would not budge. He shoved with his shoulder. He pulled the rusted handle. Nothing moved. The wood felt solid as stone. Somewhere behind it, deeper in the house, he heard a soft, wet laugh. A white shape drifted through the door as if it were open. It was a round little ghost with black eyes and small teeth. It giggled and covered its face with tiny arms. Then it peeked out at Luigi, taunting him. "That's the one that took Mario," Luigi said. Yoshi growled at the ghost. The little ghost laughed again and floated back through the sealed door. It wanted Luigi to follow. It knew he could not. Luigi banged both fists on the wood. "Open! Give me my brother!" His voice cracked. Yoshi nosed the bottom of the door and whined. There was no crack, no gap, no way through. The ghost was dragging Mario farther away with every second. Luigi's chest went tight. He was so close, and a single door had stopped him cold. Then a cold light spread across the wall. Two green flames opened in the dark, low to the floor, like eyes. A small hooded figure stepped forward. Glowing marks crawled across its ragged robe. Its face was a gray skull with green fire for eyes. Luigi grabbed the board again and put himself between the thing and Yoshi. "Don't," the little figure said. Its voice was dry and thin. "The door does not open by force. It opens by name." It raised a bony hand toward the wood. "The ghost sealed it. I keep the ways in this house. I have watched many chase the ghosts and lose themselves in the dark." Luigi's arms shook. "My brother is in there. Help me or move." The green-eyed figure studied him for a long moment. Yoshi stopped growling. He sniffed the small robed thing and sat down, quiet. That surprised Luigi. Yoshi did not trust easily. "Loyalty," the figure said, watching Yoshi. "That, the ghost cannot fake." It pressed its palm to the door. The glowing marks on its robe flared. The green light in the seams answered. With a low groan, the door swung inward. Beyond it stretched a long stairway going down into deeper dark. Wet footprints shone on the steps. Far below, the little ghost giggled, and a heavier sound answered it, something big moving in the black. The robed figure lowered its hand. "The seal is broken. But you opened the wrong door for the ghost's plan, not yours. It led you here on purpose." Luigi looked at the stairs. Cold air rose from below, carrying Mario's scent. Yoshi pressed close to his leg. The door was open now. There was no closing it again.

Luigi clicked on his flashlight and stepped onto the stairs. The beam cut a thin line through the dark. Yoshi came close behind, his claws tapping the wood. The green door hung open above them. Below, wet footprints led down into the black. Somewhere down there, Mario waited. Luigi took the steps one at a time. The cold air smelled like old water. The stairs ended in a wide room with a low ceiling. Luigi swept the light across the floor. It landed on a small white ghost with big black eyes and tiny teeth. This was Boo, the same ghost that had dragged Mario deeper into the house. Boo floated near a bright green pipe set into the far wall. It giggled and covered its face with little arms. Then it peeked out, daring Luigi to come closer. "Where is he?" Luigi said. "Where's my brother?" Boo laughed and slipped into the green pipe. But it did not go alone. Three brown creatures shuffled out of the shadows. They had round mushroom caps and angry, frowning faces. Goombas. They marched straight at Luigi with their teeth bared. Yoshi hissed and pushed in front of him. Luigi had no time to think. The lead Goomba lunged. Luigi jumped and came down hard on its cap. It flattened with a squeak and vanished in a puff. "Yoshi, the others!" Yoshi opened his mouth wide. His long tongue shot out and grabbed the second Goomba. He gulped it down in one bite, then spat out a hard egg that knocked the last one against the wall. The room went quiet. The Goombas were gone. Luigi's chest heaved, but he was still standing. Yoshi nudged his leg, proud. Luigi rubbed the little dinosaur's head. "Good boy. We did it." He pointed the flashlight at the green pipe where Boo had escaped. That was the way down. That was where Mario had gone. Luigi walked to the pipe and looked inside. The beam showed a shaft dropping far below, deeper than the stairs had gone. Warm air pushed up from the bottom, carrying the faint smell of Mario. But something was wrong. From down in the pipe came a heavy, dragging sound, slow and huge. It was not Boo. It was not a Goomba. It was much bigger than both. Luigi swallowed. He had cleared the room and found the way forward. But the ghost had led him exactly here on purpose. Whatever waited at the bottom of that pipe was the reason. He looked at Yoshi. Yoshi looked back and did not run. Luigi climbed onto the rim of the pipe. "Mario's down there. So we go down." He held the flashlight tight and dropped into the dark.

Luigi and Yoshi fell through the pipe and landed hard on cold stone. The flashlight rolled away, then stopped. Its beam showed a long room with green pipes lined along both walls. Dozens of them stood there, each dark and silent. Luigi grabbed the light and stood up. Somewhere down here, Mario was trapped inside one of these pipes. The dragging sound came again, closer now. Luigi ran to the first pipe and looked inside. Empty. He tried the next one. Empty too. "Mario!" he called. His voice bounced off the walls. No answer came back. Yoshi sniffed the floor and pulled toward the far end of the room. Luigi followed. "You smell him? Which one, boy?" A small green head popped out of a pipe. It was Koopa Troopa, a turtle in white sneakers, blinking at the flashlight. He was not one of Bowser's soldiers. He looked scared. His hands shook on the rim. "You're the one chasing the big man in red," Koopa said. "They put him deep. Down where the shell-boss keeps his prizes." Luigi crouched. "Which pipe? Show me." Koopa pointed a claw at a wide pipe at the room's end, bigger than the rest. Its rim glowed faint green. "That one drops the farthest. But you don't want to go. He's down there. The big spiked one." Koopa ducked back into his own pipe and vanished. The dragging sound turned into heavy steps. From behind the wide pipe stepped a shape Luigi already feared. Green scales. Red spikes on the shell. Bowser. He filled the far wall, blocking the pipe Koopa had shown. Boo floated at his shoulder, giggling. The ghost had led Luigi straight here, and here was the trap. "Little brother," Bowser said. His voice scraped like rock. "You came all this way to lose too." He slammed a fist. The floor shook. Yoshi crouched low and hissed. Luigi could not fight that. Not head-on. He looked at the wide pipe behind Bowser, then at the flashlight in his hand. He threw the light hard to the left. It clattered into an empty pipe and lit it bright. Bowser's head snapped toward the noise. "Now, Yoshi!" Luigi sprinted right. Yoshi shot his tongue out, wrapped a pipe rim, and pulled them both past Bowser's swinging arm. Claws raked the air behind Luigi's back. He dove headfirst into the wide glowing pipe. Yoshi tumbled in after him. Bowser's roar chased them down the shaft. They dropped and hit ground. Luigi rolled up onto his knees. In the dim glow he saw a cage of black iron. Inside it sat Mario, wrists tied, mouth taped. Their eyes met. Mario was alive. Luigi had found him at last. Then he heard Bowser drop into the pipe above, coming down fast.