Bex was on the far side of the square, milling around outside the library while the Pride of Roseville marching band warmed up. Liz was supposed to be behind me, but I couldn't see her. (Please tell me she didn't bring her molecular regeneration homework…) Mr. Smith was probably thirty feet in front of Bex, being Joe Ordinary, which was totally creeping me out. Every few moments I'd catch a flash of his black jacket as he strolled along the streets, looking like a soccer dad who was worried about the mortgage, and I remembered that of all the false façades at the Gallagher Academy, the best belonged to its people.

"How you doing up there, Duchess?" I asked, and Bex shot back, "I hate that bloody code name."

"Okay, Princess," I said.

"Cam—" Bex started, but before she could finish her threat, I heard Liz's voice in my ear.

"Chameleon, where are you?" Liz complained. "I lost you again."

"I'm over by the dunk tank, Bookworm."

"Wave your arms or something." I could almost hear Liz standing on tiptoes, peering through the crowd.

"That kind of defeats the purpose now, doesn't it?" Bex noted.

"But how am I supposed to follow you, following Smith if I can't— Oh, never mind," Liz said. "I see you."

I looked around and thought, Oh, yeah, I can see why I'd be tough to spot. I was sitting on a bench in plain sight. Seriously. I couldn't have been more out in the open if I'd had a big neon sign over my head. But that's the thing most people don't get about surveillance. No one—not even one of my best friends—was going to look twice at an ordinary-looking girl in last year's clothes sitting on a park bench eating a corn dog. If you can be still enough, and common enough, then it's really easy to be invisible.

"He's flipping," Bex said softly, and I knew it was showtime. Roseville might look like Mayberry, but Professor Smith wasn't taking any chances. He was doubling back, so I got off my bench and eased toward the sidewalk, knowing Smith was heading toward me on the opposite side of the square, past Bex, who managed to duck her head and act nonchalant. That's when a lot of people would have lost it. An amateur would have looked at her watch and spun around as if she'd just remembered some place she needed to be, but not Bex—she just kept walking.

Half the town must have turned out for the carnival, so there was lots of pedestrian cover on the sidewalk between Mr. Smith and me (a very good thing). People don't see things nearly as quickly as they see motion, so when Professor Smith turned, I stayed perfectly still. When he moved, I waited five seconds, then followed. But mostly, I remembered what my dad always said about how a tail isn't a string—it's a rubber band, stretching back and forth, in and out, moving independently of The Subject. When something interested me, I stopped. When someone said something funny, I laughed. When I passed an ice-cream stand, I bought some, all the while keeping Mr. Smith at the edge of my vision.

But that's not to say it was easy. No way. In all the times I'd imagined my first mission, I'd always thought I'd be retrieving top secret files or something. Never once did I imagine that I'd be asked to tail my COW professor through a carnival and find out what he drinks with his funnel cakes. The crazy thing was that this was SO MUCH HARDER! Professor Smith was acting as if those KGB hitmen were already on their way to Roseville—using every countersurveillance technique in the book (or at least the books I've seen), and I realized how exhausting it must be to be him. He couldn't even go out for funnel cakes without "flipping" and "corner clearing" and "breadcrumbing" all the time.

Once, things got really toasty, and I thought for sure he was going to make me, but I fell in behind a group of little old women. But then one of the women stumbled at the curb, and, instinctively, I reached out to help her. Ahead of us, Professor Smith stopped in front of a darkened storefront, staring at the reflection in the glass, but I was twenty feet behind him and shrouded by a sea of gray hair and polyester—which was a good thing. But then the women all turned to face me—which was a bad thing.

"Thank you, young lady," the older woman said. She squinted at me. "Do I know you?"

But just then, a voice blared in my ear. "Did we rotate?" Liz sounded close to panic. "Did we rotate the eyeball?"

Professor Smith was getting away, heading back in Bex's direction, so I answered, "Yes," but that only made the woman cock her eyebrow and stare harder.

"I don't remember seeing you before," the old woman said.

"Sure you do, Betty," one of the other women said, patting her friend on the arm. "She's that Jackson girl."

And that's why I'm the chameleon. I am the girl next door (it's just that our doors have fingerprint-reading sensors and are bulletproof and all…).

"Oh! Is your grandmother out of the hospital yet?" the more fragile of the women asked.

Okay, so I didn't know the Jacksons, much less how Granny was feeling, but Grandma Morgan had taught me that Chinese Water Torture is nothing compared to a grandmother who really wants to know something. I saw Professor Smith nearing Bex, but over my comms unit, Bex was laughing, saying, "Yeah, man. Go, Pirates!" as if she lived for Friday night football. Sure, Bex's definition of football might have been soccer, but boys were always boys, and a crowd of jersey-clad testosterone was assembling across the street. I didn't need surveillance photos to know who was at the center of the mob.

The old women were staring at me as if I were a needle they were trying to thread, and I said the only thing I could think of. "Dr. Smith says she needs to go south—that she needs to be toasty." I looked past the mob surrounding me and toward the one surrounding Bex, hoping she'd heard and understood that trouble was heading her way.

My hopes dwindled, though, when I heard her say, "Yeah, I love tight ends."

"Isn't that nice?" the old woman said. "Does she know where she's going?"

I saw Mr. Smith's dark jacket disappear past the pillars of the library's main entrance and then out of sight.

"You know she's such a bookworm," I said, hoping Liz was listening. "She can't wait to be near the library, just around the corner from the library, in fact," I said through gritted teeth, just as static and chaos filled my ears.

I heard Bex mutter, "Oh, no!"

Ahead of me, the football boys were heading in a pack down the street, but Bex wasn't with them. As far as I could see, Bex wasn't anywhere, and neither was Smith.

"Sorry, ladies. Gotta go," I snapped and hurried away. "Bookworm," I said, "do you have them? I have lost visual with The Subject and the eyeball. I repeat. I have lost visual with The Subject and the…"

I reached the library and looked in the direction where I'd last seen Mr. Smith, but all I saw was a long line of yellow streetlights. I weaved back through the crowd, circling the entire square, until I wound up right back where I'd started, in a vacant lot between a shoe store and City Hall, right behind the dunk tank.

I should have been more aware of my surroundings, I know—Spy 101 and all that—but it was too late. We'd been so close … soooo close. I hadn't wanted to admit it to myself, but about the time I polished off that ice-cream cone, I'd honestly started imagining what it would feel like to have Joe Solomon say, "Nice job."

But now they were gone—everyone—Smith, Bex, and Liz. I couldn't turn tail and run back to school—not then. We'd come too close. So I darted toward the funnel-cake stand, the one place we felt certain Smith would have to visit before the night was through, but I didn't pay attention to where I was going or how completely the Deputy Chief of Police filled the little seat above the dunk tank. I heard the crack of a baseball hitting metal, sensed movement out of the corner of my eye, but all the P&E training in the world wasn't enough to help me dodge the tidal wave that crashed over my shoulders.

Yeah, that's right. My first covert operations mission was also my first wet T-shirt contest, and as I stood there shivering, I knew it would probably be my last of both. People were rushing toward me, offering towels, asking if they could give me a ride home.

Yeah, I'm stealthy, I thought, as I thanked them as unmemorably as possible and darted away. Halfway down the sidewalk, I pulled a soggy twenty-dollar bill from my pocket, bought a Go Pirates! sweatshirt, and pulled it on.

In my ear, the comms unit had gone from crackling static to dense nothing, and I realized with a thud that my little silver cross, though state-of-the-art, wasn't the waterproof edition. Bex's band of football jocks strolled by, but not a single eye looked my way. As a girl, I wouldn't have minded a little corner-of-the-eye checking out, but as a spy, I was totally relieved that the whole drowned-chic look didn't undermine my covertness too much. I walked toward the funnel-cake stand, knowing that at any minute I could turn the corner on disaster—and I guess in a way, I did.

Bex and Liz were sitting together on a bench as Mr. Smith paced before them, and boy, was he scary just then. His new face had always seemed strong, but I hadn't appreciated its hard lines until he leaned over Liz and yelled, "Ms. Sutton!"

Liz started shrinking, but Bex crossed her arms and looked totally bored.

"I want to know what you are doing here!" Smith demanded.

"Ms. Baxter"—he turned to Bex—"you are going to tell me why you and Ms. Sutton have left campus. You are going to explain why you've been following me for thirty minutes, and …" I watched his expression change as something dawned on him. "And you are going to tell me where Joe Solomon is right now."

Bex and Liz looked at each other for a long time before Bex turned back to Mr. Smith. "I had a craving for a corn dog."

Well, I have already pointed out the corn dog inadequacy of the Gallagher Academy food service team, but Mr. Smith didn't buy her argument, which was just as well. He wasn't supposed to. He'd heard her real message loud and clear—Bex and Liz weren't talking.

Those are my girls.

Then I remembered that I was probably supposed to be doing something! After all, the mission wasn't over yet—not really. There was still hope. Surely I could salvage some of it. Surely…

I was really starting to hate Joe Solomon. First he sends us out to tail a guy who was almost bound to catch at least one of us, and then he doesn't teach us what to do when we get caught! Was I supposed to cause a diversion and hope Bex and Liz could slip away? Was I supposed to find a weapon and jump Smith from behind? Or was I simply supposed to stroll across the street and take my rightful place beside them on that bench of shame?

From the corner of my eye, I saw the Overnight Express truck cruise by. It could have stopped and an army could have swarmed in and saved the day, but that didn't happen; and I instantly knew why. The street was full of people who could never know the power of the girls on the bench. I could have saved the sisters, but not at the risk of the sisterhood.

"Get up," Mr. Smith told Liz. He tossed a Dr Pepper bottle into a nearby trash can. "We'll finish this discussion back at school."

I stayed in the shadows and watched Bex and Liz walk by. You know you're stealthy if your two best friends in the universe can pass within twenty feet of you and don't have a clue you're there. But it was for the best, I figured. After all, I was still a girl on a mission.