Addy spun around to stare at Nelly Day, her heart thundering like a … well, like a steam engine.

“We’re on a train!” she gasped.

The other girl’s gray eyes narrowed. Addy had the odd feeling of watching herself look suspicious.

“I been telling you,” said Nelly Day. “You been not listening.”

Addy grasped the door handle to balance herself on the shuddering floor. Either she was having a nightmare and would wake up any second, or—fffttt!—her brain had snapped and she’d gone crazy.

“This door leads to the corridor of a train?” she said. “And … other people are here too? You’re not alone? Am I part of you going crazy, or is it the other way around?”

Nelly went pink. “Don’t know why I’m talking to you. Place is full of other people. People and ServiDudes. It’s a train, isn’t it? Go look for yourself if you don’t believe me.”

Look for herself? Duh! Think on your feet, Addy! Why had she been standing around waiting for permission?

“Oh,” Addy said. “You’re still here.”

The girl glaring at her was actually Nelly Day! Addy was really, truly between the pages of Uncle Vim’s comic.

“You’ve only been gone a minute,” Nelly said. “Did you happen to see a nasty boy with ferret eyes and a mouth so mean he spits black pepper?”

“You mean Nevins?”

Nelly squinted at her. “I never heard his name. I only heard him called Insect or Scum-puppy. How do you know what it is if you’re not friendly?”

Addy shrugged. Because she and Vim had named him after a kid in her school who thought it was funny to trip people when they were carrying their lunch trays. “Isn’t he the one you were following?” she said.

“How do you know that?”

“My uncle invented you,” said Addy. “Viminy Crowe?”

“You are loco,” snapped Nelly. “One look at your … your pantaloons should have told me that. I don’t know any uncles. I have only my aunt, Isadora Fortuna, balloonist and lady adventurer.”

“Yeah, yeah,” said Addy. “More like lady thief with vengeance on her mind, although you won’t have figured that out yet.”

Nelly raised her fists, her scabby knuckles practically touching Addy’s face. “You take that back!” she snarled. “You take back saying my aunt’s a thief, or I’ll pop you one right on the noggin.”

Addy took a breath. Off on the wrong foot, as usual. No wonder most other kids thought she was prickly and unfriendly. She even annoyed fictional characters! Why was she taking this girl seriously? She had watched her uncle draw Nelly Day at the kitchen table on Balsam Road while banana-cinnamon bread baked in the oven and Addy tackled her homework.

“Hey,” she said. “I shouldn’t have said that about your aunt. Not that she’s really your aunt— Whoa!”

Nelly’s fists were dancing.

“The thing is,” Addy hurried on, “I have this … this … knowledge from this other place, and—”

“You’re a demon, aren’t you?” said Nelly. “That’s why you look like me. A spirit sent by my dead mother on the Other Side to torment me for bad deeds or rude talk. Or else you’re dead yourself! A walking corpse with an unsteady soul—”

She lowered her fists and turned to a small device set into the wall, a metal plate that looked something like a cheese grater with a red button under it. Nelly banged vigorously on the button. A faint buzzing noise came out.

“Help!” she cried, her mouth right next to the holes. “I’m”—her finger traced a number over the mesh rectangle—“in station 28, the water closet. Please notify Isadora Fortuna, stateroom 2! I am in the grip of a demon! Come at once!”

“Holy cannoli,” said Addy. “The BuzzBox works?”

When Uncle Vim decided to make the train employees robotic, he’d installed a BuzzBox in every car so the passengers could summon assistance. And here it was! The artist thought something up, he drew it and it worked!

“Where is this train going?” asked Addy.

“Toronto, of course. Isadora Fortuna will perform a stunt with her hot-air balloon that—”

“But”—Addy heard her own voice rise, matching the panic that hummed in her chest—“I was in Toronto, like, half an hour ago.”

“First you know too much, and then you know nothing,” said Nelly.

Addy leaned against the wall, head woozy. What was happening?

Uncle Vim! He would know!

She pulled her cell phone from her jeans pocket.

When in trouble call home, right?

Nelly cocked her head and took a step to get a better look.

Addy turned away from prying eyes. The home screen lit up, a close-up shot of Catnip’s pointy little rat teeth around her own finger. She speed-dialed Uncle Vim.

“What you got there?” Nelly edged nearer.

Addy jerked the phone away. “Back off. This is my cell phone. It’s …” How to explain? “It’s like a BuzzBox you carry around.” She sighed. “Only the call isn’t going through.” She shoved the phone back in her pocket. The roaming charges would be ridiculous anyway. Her mother would have a total conniption.

The door handle jiggled, and the door opened a crack. Addy banged it shut. Had Nelly’s cry on the BuzzBox actually summoned help? Or was it the ticket-taking ServiDude? In either case, not welcome.

“Ow!” said the person in the corridor.

“Aunt Isadora?” called Nelly.

“Hello?” A plaintive-sounding voice leaked through. “I’m looking for the girl I met during lunch? This is—”

It was that kid! What was he doing here?

“Wylder Wallace,” said the voice. “I’ve got your new Flynn Goster comic and … uh, something weird is going on, right? Please … uh, please let me in.” The voice faltered and started up again, along with more door-handle shaking.

If Wylder Wallace was there outside the door, Addy must be in Toronto, right? Except … Nelly was still there, fists at the ready.

“It’s okay,” Addy said to Nelly. “He won’t hurt us—he’s just irritating.”

To prove her point, the boy kept talking.

“Can you hear me? Because I’m staring at the comic and … well, you’re inside it. In the … uh, bathroom.” He whispered the last word, as if Addy might not be a human who had to pee every day of her life. “With another girl who looks exactly like you.”

“How does he know that?” Nelly whispered. “Is the whole train possessed by demons?”

Addy turned the door handle and peeked through the crack. Wylder’s worried face lit up the instant he saw her. Addy felt a strange whoosh of relief. But beyond the hunch of Wylder’s backpack and the mad flapping of the comic book in his fist, she saw blurred trees dashing by soot-smeared windows.

“Hey,” said Addy, “where are you?”

Wylder’s eyebrows came together. “I’m right in front of you. Let me in.” He waved the comic again.

“Look to your left,” said Addy. “What do you see?”

Wylder turned his head, but then his eyes snapped back to meet hers with a look that shouted, “Are you nuts?!”

“There is something weird going on,” she said. “It’s really, really important that you tell me what you see out there.”

As if Addy were a small child, Wylder enunciated every syllable of his description. “I see a long hall with a beige curtain hanging from the ceiling. A row of doors. A stack of Spiderman posters leaning against the wall. The broken train display for the Goster Summer Special, with a flickering headlight. A janitor’s bucket with a crusty old mop. And—”

“That’s enough.” Addy allowed the door to swing open. The kid grinned again, let his backpack slide off one shoulder, put the comic book inside and stepped into the room.

Nelly squealed and bumped smack into Addy, knocking her shoulder bag to the floor. Catnip spilled out from where he’d been sleeping.

“Whatever is this hullabaloo?” A new voice rippled the air.