The third time I looked back he was so far behind and swallowed by the crowd that I could hardly see him. Maybe he didn’t really care whether he caught us. After all, we were neither a great threat nor much of a prize. Maybe the dog had been right: compared to an ymbryne, we were hardly worth the trouble.

Halfway to the exits the crowd thinned enough for us to break into an open run—but we’d taken only a few strides when Emma caught me by the sleeve and stopped me. “Addison!” she cried, spinning to look around. “Where’s Addison?”

A moment later he came scampering out of the thickest part of the crowd, a long piece of white fabric trailing from a spike on his collar. “You waited for me!” he said. “I became entangled in a lady’s stocking …”

Heads turned at the sound of his voice.

“Come on, we can’t stop now!” I said.

Emma plucked the stocking from Addison’s collar, and we were off and running again. Before us were an escalator and an elevator. The escalator was working but very crowded, so I steered us toward the elevator instead. We ran past a lady painted blue from head to toe, and I had to turn and stare even as my legs carried me onward. Her hair was dyed blue, her face caked with blue makeup, and she wore a skin-tight jumpsuit, also blue.

She’d only just passed out of sight when I saw someone even more freakish: a man whose head was divided vertically into halves, one bald and burned to a crisp, the other untouched, hair moussed into a dapper wave. If Emma noticed him, she didn’t turn to look. Maybe she was so used to meeting genuine peculiars that peculiar-looking normals hardly registered. But what if they aren’t normal? I thought. What if they’re peculiars, and instead of the present we’ve ended up in some new loop? What if—

Then I saw two boys with glowing swords battling by a wall of vending machines, each sabre clash sounding with a thin plasticky thwack, and reality came into sharp focus. These strange-looking people weren’t peculiars. They were nerds. We were very much in the present.

Twenty feet away, the elevator doors opened. We poured on the speed and hurled ourselves inside, bouncing off the back wall with our hands while Addison tumbled in on tripping legs. I turned just in time to glimpse two things through the closing doors: the wight breaking out of the crowd and coming at us in a full run, and back by the tracks where the train was pulling away, the hollowgast leaping from the roof of the last car to the station ceiling, swinging like a spider from a light fixture by its tongues, its black eyes burning at me.

And then the doors closed and we were gliding gently upward, and someone was saying, “Where’s the fire, mate?”

A middle-aged man stood in the rear corner of the elevator, costumed and sneering. His shirt was torn, his face was crosshatched with fake cuts, and strapped to the end of one arm, Captain Hook–style, was a bloodstained chainsaw.

Emma saw him and took a quick step back. “Who are you?”

He looked mildly offended. “Oh, come on.”

“If you really want to know where the fire is, don’t answer.” She began to raise her hands, but I reached over and stopped her.

“He’s no one,” I said.

“I thought I was making such an obvious choice this year,” the man muttered. He arched an eyebrow and raised his chainsaw a little. “Name’s Ash. You know … Army of Darkness?”

“Never heard of either,” said Emma. “Who’s your ymbryne?”

“My what?”

“He’s just doing a character,” I tried to explain, but she wasn’t hearing me.

“Never mind who you are,” she said. “We could use an army, and beggars can’t be choosers. Where are the rest of your men?”

The man rolled his eyes. “L-O-L. You guys are funny. Everyone’s in the convention center, obviously.”

“He’s wearing a costume,” I whispered to Emma. Then, to the guy: “She doesn’t see a lot of movies.”

“A costume?” Emma scrunched her brow. “But he’s a grown man.”

“So what?” the man said, looking us up and down. “And who are you supposed to be? Walking Dorks? League of Extraordinary Dingleberries?”

“Peculiar children,” said Addison, whose ego wouldn’t allow him to be silent any longer. “And I am the seventh pup of the seventh pup in a long and illustrious line of—”

The man fainted before Addison could finish, his head knocking against the floor with a clonk that made me wince.

“You’ve got to stop doing that,” Emma said, then grinned despite herself.

“Serves him right,” said Addison. “What a rude person. Now quick, nick his wallet.”

“No way!” I said. “We’re not thieves.”

Addison snorted. “I daresay we need it more than he does.”

“Why on earth is he dressed like that?” said Emma.

The elevator dinged and the doors began to slide open.

“I think you’re about to find out,” I said.

* * *

The elevator doors split open and like magic the day-lit world spread before us, so bright we had to shield our eyes. I drew a welcome lungful of fresh air as we stepped out onto a swarming sidewalk. There were costumed people everywhere: superheroes in spandex, zombies shambling in heavy makeup, raccoon-eyed anime girls wielding battleaxes. They congregated in unlikely bunches and spilled into a street blocked off to traffic, drawn like moths to a large gray building where a banner proclaimed: COMIC CONVENTION TODAY!

Emma recoiled toward the elevator. “What is all this?”

Addison peered over his glasses at a green-haired Joker touching up his face paint. “Judging by their attire, it appears to be some sort of religious holiday.”

“Something like that,” I said, coaxing Emma back onto the sidewalk, “but don’t be scared—they’re only dressed-up normals, and that’s what we look like to them, too. We only need to worry about that wight.” I failed to mention the hollow, hoping we’d baffled it by vanishing into the elevator. “We should find a place to hide until he’s gone, then sneak back into the Underground …”

“No need for that,” Addison said, and he trotted into the crowded street, nose twitching.

“Hey!” Emma called after him. “Where are you going?”

But he was already circling back.

“Huzzah for fortune!” he said, wagging his stubby tail. “My nose tells me our friends were brought out of the underground here, via that escalator. We’ve gone the right way after all!”

“Thank the birds!” Emma said.

“Do you think you can follow their trail?” I asked.

“Do I think I can? They don’t call me Addison the Astounding for nothing! Why, there isn’t an aroma, a redolence, a peculiar eau de toilette I couldn’t nose from a hundred meters—”

Addison was easily distracted by the topic of his own greatness, even when pressing matters were at hand, and his proud, booming voice had a tendency to carry.

“Okay, we get it,” I said, but he steamrolled on, walking now, following his nose.

“… I could find a peculiar in a hollow-stack, an ymbryne in an aviary …”

We chased him into the costumed crowd, between the legs of a dwarf on stilts, around a pack of undead princesses, and on a near-collision course with a Pikachu and an Edward Scissorhands, who were waltzing in the street. Of course our friends were brought this way, I thought. It was perfect camouflage—not only for us, who amidst all this looked downright normal, but also for wights abducting a herd of peculiar children. Even if some of them had dared cry out for help, who would’ve taken them seriously enough to intervene? People were play-acting all around us, improvising staged fights, growling in monstrous costumes, moaning like zombies. Some strange kids yelling about being kidnapped by people who wanted to steal their souls? Wouldn’t raise an eyebrow.

Addison walked a circle sniffing the ground, then sat down, perplexed. Subtly, because even in this crowd a talking dog would be shocking, I bent down and asked him what was the matter.