Thirty minutes later I was in my uniform, making my way down the spiral staircase, toward the Grand Hall with the rest of the student body. Well, most of the student body.

"Where's Macey?"

"Oh, she's back already," Liz said, but I knew that much. After all, it was kind of hard to miss Macey's closetful of designer clothes, her stash of ridiculously expensive skin care products (many of which are legal only in Europe), and the fact that someone had very recently been sleeping in her bed.

The last time I'd seen our fourth roommate, she'd been preparing for three weeks in the Swiss Alps with her senator father, her cosmetics-heiress mother, and a celebrity chef from the Food Channel; but Macey McHenry had come back early. And now she was nowhere to be seen.

Bex was looking around, too, staring over the heads of the seventh graders walking in front of us. "She said she had a bit of research to do in the library, but that was hours ago. I thought she'd meet us down here, but…" she trailed off, still looking.

"You guys go eat," I said, stepping away from the crowd and starting down the hall. "I'll find her."

I pulled open the heavy library doors and stepped inside the massive bookshelf-lined room. Comfy leather couches and old oak tables surrounded a roaring fire. And there, in the center of it all, was Macey McHenry. Her head was resting on the latest edition of Molecular Chemistry Monthly, pink highlighter marks were on her cheek, and a puddle of drool had run from her mouth to the wooden desktop.

"Macey," I whispered, reaching out to gently shake her shoulder.

"What? Huh…Cammie?" She struggled upright and blinked at me. "What time is it?" she cried, jumping up and knocking a stack of flash cards to the floor.

I bent down to help her pick them up. "The welcome-back dinner is about to start."

"Great," she said, sounding like someone who didn't think it was great at all.

Her glossy black hair stuck out at odd angles, and her normally bright blue eyes were dazed with sleep. Even though I knew better, I couldn't help but say, "So, did you have a nice break?"

She cut me a look that could kill (and will—just as soon as our head scientist, Dr. Fibs, perfects his looks-can-kill technology).

"Sure." Macey blew a stray piece of hair away from her beautiful face and pulled the last of the flash cards into a pile. "Right up until my parents saw my grades."

"But you got great grades! You covered nearly two semesters' worth of work. You—"

"Got four A's and three B's," Macey finished for me.

"I know!" I cried. After all, I had personally tutored Macey in the finer points of macroeconomics, molecular regeneration, and conversational Swahili.

"And according to the Senator," Macey said, keeping up her unspoken vow never to call her father by name, "there's no way I am capable of earning four A's and three B's, so therefore I must be cheating."

"But …" I struggled to find the words. "But…Gallagher Girls don't cheat!" And it's true. Not to sound dramatic or anything, but a Gallagher Girl's real grades don't come in pass or fail—they're measured in life or death. But Senator McHenry didn't know that. I looked at the gorgeous debutante who had flunked out of every prep academy on the East Coast and was now earning A's and B's at spy school, and I realized the senator didn't know a lot of things. Not even his own daughter.

The library was empty around us, but I still lowered my voice as I said, "Macey, you should tell my mom. She could call your dad. We could—"

"No way!" Macey said, as if I never let her have any fun. "Besides, I already know what I'm going to do."

We'd reached the heavy doors of the library, but I paused for the answer. "What?"

"Study." Macey cocked a perfectly plucked eyebrow. "Next time I'll get all A's." And then she smiled as if, after sixteen years of practice, she'd finally found the ultimate way to defy her parents.

I heard voices in the corridor outside, which was strange because at that moment the entire Gallagher Academy student body was waiting in the Grand Hall. Something made us freeze. And wait. And despite the heavy doors between us, I could clearly hear my mother say, "No, Cammie doesn't know anything."

Well, as a spy (not to mention a girl), there are many, many sentences that will make me stop and listen, and, needless to say, "Cammie doesn't know anything" is totally one of them!

I leaned closer to the door while, beside me, Macey's big blue eyes got even wider. She leaned in and whispered, 'What don't you know?"

"She didn't suspect anything?" Mr. Solomon, my dreamy CoveOps instructor, asked.

"What didn't you suspect?" asked Macey.

Well, of course the whole point of not knowing and not suspecting is that I neither knew nor suspected, but I couldn't point that out because, at the moment, my mother was on the opposite side of the door saying, "No, she was being debriefed at the time."

I thought back to the long, quiet ride from D.C., the way my mother had stared at the frosty countryside as she'd told me that she hadn't watched my interrogation—that she'd had things to do.

"We can't tell her, Joe," Mom said. "We can't tell anyone. Not until we have to."

"Not about black thorn?"

"Not about anything." And then Mom sighed. "I just want things to stay as normal as possible for as long as possible."

I looked at Macey. Normal had just taken on a whole new meaning.

After they left, Macey and I slipped back to the Grand Hall and the sophomore table. Mom had already taken her place at the front of the room. I know that Liz whispered, "What took you so long?" as we sat down. But beyond that, I wasn't sure of anything, because, to tell you the truth, I was having a little trouble hearing. And talking. And walking.

All moms have secrets—mine more than most—and even though I've always known that there are lots of things my mother can never tell me, it had never occurred to me that there were things she might be keeping from me. It may not sound like a big difference, but it is.

Mom gripped the podium in front of her and looked out at the hundred girls who sat ready for a new semester. "Welcome back, everyone. I hope you had a wonderful winter break," she said.

"Cammie," Bex whispered, eyeing me and then Macey. "Something's going on with you two. Isn't it?"

Before I could answer, my mother continued, "I'd like to begin with the very exciting news that this semester we will be offering a new course, History of Espionage, taught by Professor Buckingham." Light applause filled the Grand Hall as our most senior staff member gave a small wave.

"And also," my mother said slowly, "as many of you have no doubt noticed, the East Wing will be off-limits for the time being, since recent work to the mansion revealed that it has been contaminated by fumes from the chemistry labs."

"Cammie," Liz said, scooting closer, "you look kind of… pukey."

Well I felt kind of pukey.

"And most of all," my mother said, "I want to wish everyone a great semester."

The silence that had filled the hall a moment before evaporated into a chorus of talking girls and passing plates. I tried to turn the volume down, to listen to the thoughts that swirled inside my mind like the snow that blew outside. I closed my eyes tightly, forcing the room to dissolve away, until suddenly, everything became clear.

And I whispered the fact that I'd known for years but only just remembered.

"There is no ventilation access from the chem labs to the East Wing."

Chapter Three

There are many pros and cons to living in a two-hundred-year-old mansion. For example: having about a dozen highly secluded and yet perfectly inbounds places where you can sit and discuss classified information: PRO.

The fact that none of these places are well heated and/or insulated when you are discussing said information in the middle of the winter: CON.

Two hours after our welcome-back dinner, Macey was leaning against the stone wall at the top of one of the mansion's tallest towers, drawing her initials on the window's frosty panes. Liz paced, Bex shivered, and I sat on the floor with my arms around my knees, too tired to get my blood flowing despite the chill that had seeped through my uniform and settled in my bones.

"So that's it, then?" Bex asked. "That's everything your mom and Mr. Solomon said? Verbatim?"

Macey and I looked at each other, recalling the conversation we'd overheard and the story we'd just told. Then we both nodded and said, "Verbatim."

At that moment, the entire sophomore class was probably enjoying our last homework-free night for a very long time (rumor had it Tina Walters was organizing a Jason Bourne-athon), but the four of us stayed in that tower room, freezing our you-know-whats off, listening for the creaking hinges of the heavy oak door at the base of the stairs that would warn us if we were no longer alone.

"I can't believe it," Liz said as she continued to walk back and forth—maybe to keep warm, but probably because…well…Liz has always been a pacer. (And we've got the worn spots on our bedroom floor to prove it.)

"Cam," Liz asked, "are you sure the East Wing couldn't have been contaminated by fumes from the chem labs?"

"Of course she's sure," Bex said with a sigh.

"But are you absolutely, positively, one hundred-percent sure ?" Liz asked again. After all, as the youngest person ever published in Scientific American, Liz kind of likes things verified, cross-referenced, and proven beyond a shadow of a doubt.

"Cam," Bex said, turning to me, "how many ventilation shafts are there in the kitchen?"

"Fourteen—unless you're counting the pantry. Are you counting the pantry?" I asked, which must have been enough to prove my expertise, because Macey rolled her eyes and sank to the floor beside me. "She's sure."

In the dim light of the cold room I could see snowflakes swirl in the wind outside, blowing from the mansion's roof (or … well…the parts of the roof that aren't protected with electrified security shingles). But inside, the four of us were quiet and still.

"Why would they lie?" Liz asked, but Bex, Macey, and I just looked at her, none of us really wanting to point out the obvious: Because they're spies.

It's something Bex and I had understood all our lives. Judging by the look on her face, Macey had caught on, too (after all, her dad is in politics). But Liz hadn't grown up knowing that lies aren't just the things we tell—they're the lives we lead. Liz still wanted to believe that parents and teachers always tell the truth, that if you eat your vegetables and brush your teeth, nothing bad will ever happen. I'd known better for a long time, but Liz still had a little naivete left. I, for one, hated to see her lose it.

"What's black thorn?" Macey asked, looking at each of us in turn. "I mean, you guys don't know either, right? It's not just a me-being-the-new-girl thing?"

Everyone shook their heads no, then looked to me. "Never heard of it," I said.

And I hadn't. It wasn't the name of any covert operation we'd ever analyzed, any scientific breakthrough we'd ever studied. Black thorn or Blackthorne or whatever could have been anyone, anything, anywhere! And whoever … or whatever … or wherever it was, it had made my mother miss some quality mother-daughter interrogation time. It had also forced my Covert Operations instructor to hold a clandestine conversation with my headmistress. It had crept inside the Gallagher Academy for Exceptional Young Women (or at least its East Wing), and so there we were, not quite sure what a Gallagher Girl was supposed to do now.