WHY IS THERE A HOUSE GROWING OUT OF THIS TRAIN?

The demon hauled itself into the world, shredding reality as it came.

It was like somebody had cut its shape from the train roof, the metal shearing loose into a structure of teeth and claws. Sparks detonated into the night as it tugged its bulk free—something halfway between a spider and a dog. It slipped on the metal, its back end falling into the car below, its huge claws gouging the roof for purchase. It had no eyes, but it didn’t need them. Its elongated snout sniffed at the air, turned toward Marlow, and peeled open like a crocodile’s. Then the demon lunged, faster than it looked, those jaws snapping shut so hard that they punched out a shock wave of air.

Marlow staggered back, colliding with Night. She grabbed hold of his arm, both of them trying to stay upright on the trembling train. The demon threw itself at them, scuttling on eight or nine legs. It had moved only a few feet, though, before it exploded with the force of a car bomb.

Behind it, the redhead was already plunging her blade into the next section of roof. Another demon was forming there, its birthing scream louder even than the roar of the wind. This one dropped inside the hole it crawled out of and Marlow could hear the cries from inside the train, could smell the slaughterhouse stench as it carved its way through whoever was down there.

“I got a million more,” the redhead yelled, retreating toward the front of the train. “This knife opens a hole between worlds.”

She ducked down and jammed the blade into the roof again. Inside the car there was a muffled detonation, the windows shattering as the second demon exploded. The next one was on the move, long and stick-insect thin, struggling on three needle-shaped legs. It lost purchase, slipping off the side of the train, its flailing limbs almost decapitating Marlow as it spun past into the darkness.

“How the hell is she doing that?” asked Night, her hand still on Marlow.

He shook his head. It was the wrong question. The right one was how were they supposed to get close enough to stop her?

The redhead spun the knife in her fingers. Past her, the engine barreled onward, visible a couple of cars ahead as it arced around a wide bend in the track. Marlow smudged the tears from his eyes, hunkered down closer to the roof. It had to be an illusion, but it looked like something was growing out of it. The car was changing, getting taller, sash windows appearing in its bulk. So many sparks were shooting from the wheels that it looked almost as if the train were a speedboat traveling on a lake of fire.

“Marlow,” said Night, leaning in to him. “Why is there a house growing out of the front of this train?”

Not an illusion, then.

There was something else up there, too. Something beyond the impossible train. It looked like a darker patch of night, almost solid. Then he understood that it was solid. They were hurtling toward a mountain.

Right into a tunnel.

“Hey!” he called, waving his hands at the redhead. “You … uh. Nice wig, my mom has one just like it.”

“What?” said Night. “A wig?”

The redhead was frowning but he wasn’t sure if it was because she hadn’t heard or hadn’t understood. Either way, it was working. The pitch-black bulk of the mountain grew behind her, the mouth of the tunnel somehow even darker, like it had been cut right out of time and space.

Just a few seconds more.

“How do you keep it on in this wind?” he yelled. “Glue? Duct tape?”

The redhead yelled back, but her words were snatched away by the wind. She lifted the knife over her head, ready to plunge it down again. Behind her the tunnel mouth opened wide, the top surely low enough to rip her head clean off. Marlow grabbed the roof, sinking his fingers into the metal, bracing himself. Night must have seen it, too, because she swore, throwing herself onto her stomach.

The front of the train punched into the tunnel hard enough to demolish the top of the building that was growing there. It was enough of a warning, the redhead dropping without even looking back. Then they were sucked into the tunnel so hard and fast that Marlow’s lungs locked, his whole body tight with panic. He couldn’t even scream, just clenched his jaw so hard he thought his teeth might shatter. A few feet above his head the ceiling ripped by, light fixtures whumping past his ears like bullets.

Ahead, bathed in weak orange light, the redhead fumbled with the knife and thrust it up into the ceiling. She screamed, the speed of the train ripping the blade from her fingers. Not before another demon had crawled loose from the wound in the tunnel roof, though, this one as big as Truck and almost as ugly. It shook itself like a bear, its face made up of a chunk of concrete and rock and half of a light fixture—the yellow plastic cover looking almost like an eye.

It roared, pushing itself up, strong enough to tear pieces from the tunnel walls. Then they were sucked out into the night again, the pressure change like daggers in his ears. The bear demon charged at him on all fours.

Come on, Marlow thought, bracing himself. Explode.

It didn’t. It bouldered over the gap between cars and then it was too late. Marlow started to run toward it, an instant of slow motion where he could see the demon’s immense torso—made of rubble and concrete but as flexible as dough—and the way the ugly mess of its head seemed to open like it was hinged, the gaping darkness of its throat visible beyond. Then they collided, a tackle that shook every single bone in his body to dust.

The momentum of the demon spun Marlow around but he managed to keep his feet on the roof, his hands gripping fistfuls of stony flesh. He punched it once, not caring where, shrapnel exploding from his knuckles. It howled again, blasting Marlow with the stench of sulfur. He ducked under its jaws, felt a claw peel open the skin of his back. The pain was so intense it didn’t feel real, and he launched an uppercut into the demon’s chest, following it with a punch to the head. It teetered back, found its balance, started forward again, then blew itself into chunks.

Night hopped over the debris, reached his side, and together they looked toward the front of the train. The redhead stood there, glaring back at them. Then she glanced to the side, took a deep breath, and hurled herself into the darkness. Behind her the engine car was more distorted than ever—that same brick building seeming to grow up into the night. Even as he watched, Marlow saw a neon light flicker into life.

“This is really weird,” he yelled above the roar of the wind.

“You think?” said Night. “Come on.”

She set off, taking her time so as not to slip on the remains of the demons. The train seemed to be traveling faster than ever, tearing around another bend in the track. Marlow was leaping between cars when the wall of mountains to both sides gave way and the world opened up onto a vista of silver. There was an immense canyon right ahead, bathed in moonlight. Crossing it was a bridge that could have been the remains of a dragon—skeletal ribs and arches that must have stretched five hundred feet to the other side.

Speeding train. Bridge. Demons. Canyon.

Not a good combination.

He dug deep, broke into a sprint—everything but him slowing to a crawl. The locomotive was actually morphing, pieces of metal splintering into spinning fractal shapes before reassembling themselves into bricks and guttering. It was back to the height it had been when they’d entered the tunnel, and growing fast. Marlow could make out drywall, pipes, even a toilet in the shifting mass of its interior.

He was halfway down the penultimate car when a different force hit him—like a sledgehammer in the stomach. He faltered, skidding onto his knees and clutching himself. It felt like everything that made him him had suddenly festered inside, turned to rot. Night had stopped right next to him and the expression on her face said it all. He knew this feeling. He’d experienced it once before.

Back at his school.

Back when it had been destroyed.

“Mammon,” he whispered. Night clenched her fists and kept moving, her body leaning into the wind. She reached the gap between the car and the engine—the building—and stopped.

Marlow growled against his terror, forced one foot forward, then another, until he was standing next to her. The building was close enough to touch. Definitely not an illusion. Those were real bricks, covered with real grime, daubed with real graffiti. The flickering neon light looked like it had been cut in half, reading otel.

“Hey, anytime you’re ready.”

Marlow glanced at Night, then nodded. He reached down and grabbed the edge of the roof, peeling it back like he was opening a sardine can. The car below was drenched in darkness, the only light coming from the sparking wheels. He thought he heard a voice down there.

Night hopped in, making no sound as she landed. He leaped after her, landing on a floor that had to be asphalt, wet with a rain that wasn’t falling outside. Right ahead of them was the door to the next car, leading into the darkness of the connecting corridor. The squirming in Marlow’s guts was worse than ever, and there was definitely somebody speaking.

Pan.

He pushed through the door, slipping on the wet asphalt. Through the final door the world was alight, bathed in illumination so bright that it might have burned right through his skull. He could make out a silhouette in the cold fire, one that looked Pan-shaped.

“That you guys?” somebody said behind him and he almost screamed. It was Truck, scrambling in from the car, that fire extinguisher still gripped in his hands. “This is really weird.”

“Yeah, we got that,” said Marlow, blinking spots of light from his vision.

“I think it’s … I think she’s in there with Mammon,” Truck said.

“Yeah, we got that, too,” Night said.

“We should probably go help,” said Marlow.

“Yeah,” Night replied. But nobody moved. Marlow glanced at her, then at Truck.

“Hey,” the big guy said, shrugging. “I’m powerless, unless she’s on fire.”

“Mind if I borrow it?”

“Be my guest,” said Truck, holding the extinguisher out.

Marlow took it. It was a poor weapon, especially against something like Mammon. But what else could he do? Taking a breath, he pushed through the door.