Scout headed toward the stairs, which she took at a trot. I hung back until I was sure she wouldn’t see me as she rounded the second flight of stairs, then followed her down. When she reached the first floor, she headed through the Great Hall, which, even after the required study period, still held a handful of apparently ambitious teenagers. Unfortunately, the aisle between the tables was straight and empty, so if Scout turned around, my cover was blown.

I took a breath and started walking. I made it halfway without incident when, suddenly, Scout paused. I dumped into the closest chair and bent down, faking an adjustment to my flip- flop. When she turned around again and resumed her progression through the room, I stood up, then hustled to squeak through the double doors before they closed behind her.

I just made it through, then flattened myself against the wall of the hallway that led to the domed center of the main building. I peeked around the corner; Scout was hurrying across the tiled labyrinth. I gnawed my lip as I considered my options. This part of playing the new Nancy Drew was tricky—the room was gigantic and empty, at least in the middle, so there weren’t many places to hide.

Without cover, I decided I’d have to wait her out. I watched her cross the labyrinth and move into the hallway opposite mine, then pause before a door. She looked around, probably to see whether she was alone (we’re all wrong sometimes), then slipped the ribboned key from her neck and slid the key into the lock.

The click of tumblers echoed across the room. She winced at the sound, but placed a hand on the door, took a final look around, and disappeared. When she was gone, I jogged across the labyrinth to the other side, then pressed my ear to the door she’d closed behind her. After the sound of her footsteps receded, I twisted the doorknob, found that it was still unlocked and—heart beating like a bass drum in my chest—edged it open.

It was another hallway.

I blew out the breath I’d been holding.

A hallway wasn’t much to get stressed out about. Frankly, the chasing was getting a little repetitive. Hallway. Room. Hallway. Room. I reminded myself that there was a greater purpose here—spying on the girl who’d adopted me as a best friend.

Okay, put that way, it didn’t sound so noble.

Morally questionable or not, I still had a job to do. I walked inside and closed the door behind me. I didn’t see Scout, but I watched her elongated shadow shrink around the corner as she moved. I followed her through the hallway, and then down another set of stairs into what I guessed was the basement, although it didn’t look much different from the first floor, all limestone and golden light and iron sconces. The ceiling was different, though. Instead of the vaults and domes on the first floor, the ceiling here was lower, flatter, and covered in patterned plaster. It looked like a lot of work for a basement.

The stairs led to another hall. I followed the sound of footsteps, but only made it five or six feet before I heard another sound—the clank and grate of metal on metal. I froze and swallowed down the lump of fear that suddenly tightened my throat. I wanted to call her name, to scream it out, but I couldn’t seem to draw breath to make a sound. I forced myself to take another step forward, then another, nearly jumping out of my skin when that bone-chilling gnash of metal echoed through the hallway again.

Oh, screw this, I thought, and forced my lungs to work. “Scout?” I called out. “Are you okay?”

When I got no response, I rounded the corner. The hallway dead-ended in a giant metal door . . . and she was nowhere to be seen.

“Frick,” I muttered. I glanced around, saw nothing else that would help, and moved closer so I could give the door a good look-see.

It was ginormous. At least eight feet high, with an arch in the top, it was outlined in brass rivets and joints. In the middle was a giant flywheel, and beneath the flywheel was a security bar that must have been four or five inches of solid steel. It was in its unlocked position. That explained the metal sounds I’d heard earlier.

I wasn’t sure I wanted to know what that door was keeping out of St. Sophia’s, but Scout was in there. Sure, we hadn’t known each other long, and I wasn’t up on all the comings and goings of her community improvement group, but this seemed like trouble . . . and help was the least I could offer my new suitemate.

After all, what were they going to do—kick me out?

“Sagamore, here I come,” I whispered, and put my hands on the flywheel. I tugged, but the door wouldn’t open. I turned the flywheel, clockwise first, then counterclockwise, but the movement had no effect—at least, not on this side of the door.

Frowning, I scanned the door from top to bottom, looking for another way in—a keyhole, a numeric pad, anything that would have gotten it open and gotten me inside.

But there was nothing. So much for my rescue mission.

I considered my options.

One: I could head back upstairs, tuck into bed, and forget about the fact that my new best friend was somewhere behind a giant locked door in an old convent in downtown Chicago.

Two: I could wait for her to come back, then offer whatever help I could.

I nibbled the edge of my lip for a moment and glanced back at the hallway from which I’d come, my passage back to safety. But I was here, now, and she was in there, getting into God only knew what kind of trouble.

So I sat down on the floor, pulled up my knees, and prepared to wait.

I don’t know when I fell asleep, but I jolted awake at the sound of footsteps on the other side of the door. I jumped up from my spot, the flip-flops I’d pulled off earlier still in my hand, my only weapon. As I faced down the door with only a few inches of green foam as protection, it occurred to me that there might be a stranger—and not Scout—on the other side of the door.

My heart raced hammerlike in my chest, my fingers clenched into the foam of my flip- flops. Suddenly the flywheel began to turn, the spokes rotating clockwise with a metallic scrape as someone sought entrance to the convent basement. Seconds later, oh so slowly, the door began to open, hundreds of pounds of metal rotating toward me.

“Don’t come any closer!” I called out. “I have a weapon.”

Scout’s voice echoed from the other side of the door. “Don’t use it! And get out of the way!”

It wasn’t hard to obey, since I’d been bluffing. I stepped aside, and as soon as the crack in the door was big enough to squeeze through, she slipped through it, chest heaving as she sucked in air.

She muttered a curse and pressed her hands to the door. “I’m going to rail on you in a minute for following me, but in the meantime, help me close this thing!”

Although my head was spinning with ideas about what, exactly, she’d left on the other side of the door, I stepped beside her. With both pairs of hands on the door, arms and legs outstretched, we pushed it closed. The door was as heavy as it was high, and I wondered how she’d gotten it open in the first place.

When the door was shut, Scout spun the flywheel, then reached down to slide the steel bar back into its home. We both jumped back when a crash echoed from the other side, the door shaking on its giant brass hinges in response.

Eyes wide, I stared over at her. “What the hell was that?”

“Litter,” Scout said, staring at the closed door, as if making sure that whatever had been chasing her wasn’t going to breach it.

When the door was still and the hallway was silent, Scout turned and looked at me, her bob of blond hair in shambles around her face, jacket hanging from one shoulder . . . and fury in her expression.

“What in the hell do you think you’re doing down here?” She pushed at the hair from her face, then pulled up the loose shoulder of her jacket.

“Exercising?”

Scout put her hands on her hips, obviously dubious.

“I was afraid you were in trouble.”

“You were nosy,” she countered. “I asked you to trust me on this.”

“Trusting you about a secret liaison is one thing. Trusting you about your safety is something else.” I bobbed my head toward the door. “Call it community improvement if you want, but it seems pretty apparent that you’re involved in something nasty. I’m not going to just stand by and watch you get hurt.”

“You’re not my mother.”

“Nope,” I agreed. “But I’m your new BFF.”

Her expression softened.

“I don’t need all the details,” I said, holding up my hands, “but I am going to need to know what the hell was on the other side of that door.”

As if on cue, a crash sounded again, and the door jumped on its hinges.

“We get it already!” she yelled. “Crawl back into your hole.” She grabbed my arm and began to pull me down the hall and away from the ominous door. “Let’s go.”

I tugged back, and when she dropped my arm, slipped the flip-flops back onto my feet. She was trucking down the hall, and I had to skip to keep up with her. “Is it an axe murderer?”

“Yeah,” she said dryly. “It’s an axe murderer.”

Most of the walk back was quiet. Scout and I didn’t chat much, and both the main building and the Great Hall were dark and empty of students. The moonlight, tinted red and blue, that streamed through the stained glass windows was the only light along the way.

As we moved through the corridors, Scout managed not to look back to see whether the basement door had been breached or whether some nasty thing was on our trail. I, on the other hand, kept stealing glances over my shoulder, afraid to look, but more afraid that something would sneak up behind us if I didn’t. That the corridors were peacefully quiet didn’t stop my imagination, which made shapes in the shadows beneath the desks of the Great Hall when we passed through it.

Exactly what had been behind that door? I decided I couldn’t hold in the question any longer. “Angry drug dealer?” I asked her. “Mental institution escapee? Robot overlord?”

“I’m not aware if robots have taken us over yet.” Her tone was dry.

“Flesh-eating zombie monster?”

“Zombies are a myth.”

“So you say,” I muttered. “Just answer me this: Are you in cahoots with those Montclare guys?”

“What is a ‘cahoot,’ exactly?”

“Scout.”

“I was exercising. Great workout. I got my heart rate up, and I got into the zone.” Her elbow bent, she pumped one arm as if lifting a dumbbell.

When we opened the door to the building that held our dorm rooms, I pulled her to a stop. She didn’t look happy about that.

“You were being chased,” I told her. “Something behind that door was after you, and whatever it was hit the door after we closed it.”

“Just be glad we got the door closed.”

“Scout,” I said. “Seriously. What’s going on?”

“Look, Lily, there are things going on at this school—just because things seem normal doesn’t mean they are. Things are rarely what they seem.”

Things hardly seemed normal, from late- night disappearances, to the coincidental meeting of the boys next door, to this. And all of it within my first twenty-four hours in Chicago. “Exactly what does that mean, ‘rarely what they seem’?”

She arched an eyebrow at me. “You said you had a weapon.” She scanned me up and down. “Exactly what weapon was that? Flip-flops?”

I held up a foot and dangled my thick, emerald green flip-flop in front of her. “Hey, I could have beaned a pursuer on the head with this thing. It weighs like ten pounds, and I guarantee you he would have thought twice before invading St. Sophia’s.”

“Yeah, I’m sure that would hold them off.” At my arch expression, she held up her hands. “Fine. Fine. Let’s say, for the sake of argument, that I’m in a club for gifted kids. Of a sort.”

“A club for gifted kids. Like, what kind of gifted?” Gifted at fibbing came immediately to mind.

“Generally gifted?”

The room was silent as I waited in vain for her to elaborate on that answer.

“That’s all you’re going to tell me?”

“That’s as much as I can tell you,” she said, “and I’ve already said too much. I wish I could fill you in, but I really, really can’t. Not because I don’t trust you,” she said, holding up a defensive hand. “It’s just not something I’m allowed to do.”

“You aren’t allowed to tell me, or anyone else, that something big and loud and powerful is hanging out beneath a big-ass metal door in the basement? And that you go down there willingly?”

She nodded matter-of-factly. “That’s pretty much it.”

I blew out a breath and shook my head. “You’re insane. This whole place is insane.”

“St. Sophia’s has a lot to offer.”

“Other than nighttime escapades and maniacs behind giant cellar doors?”

“Oh, those aren’t even the highlights, Lil.” Scout turned and resumed the trek back home.

When we reached the suite, Scout walked toward her room, but then paused to glance back at me.

“Whatever you’re involved in,” I told her, “I’m not afraid.” (My fingers were totally crossed on that one.) “And if you need me, I’m here.”

I could tell she was tired, but there was a happy glint in her eyes. “You rock pretty hard, Parker.”

I grinned at her. “I know. It’s one of my better qualities.”