"What?" she said to me. I could see myself reflected in the lenses of her glasses, small and out of perspective. "What are you looking at?"

I felt my face flush, as it did anytime anybody raised their voice at me. I was entirely too sensitive to tone, so much so that even TV court shows could get me upset—I always had to change the channel when the judge ripped into anyone. "Nothing," I said, and turned back around.

A moment later, the high-school guy working the snack bar waved me up with a tired look. While he poured my drink I could feel the girl behind me, her presence like a weight, as I smoothed my two bills out flat on the glass beneath my fingers, concentrating on getting every single crease. After I paid, I walked away, studiously keeping my eyes on the pocked cement of the walkway as I made my way back around the deep end to where my best friend, Clarke Reynolds, was waiting.

"Whitney said to tell you she's going home," she said, blowing her nose as I carefully put the Coke on the pavement beside my chair. "I told her we could walk."

"Okay," I said. My sister Whitney had just gotten her license, which meant that she had to drive me places. Getting home, however, remained my own responsibility, whether from the pool, which was walking distance, or the mall one town over, which wasn't. Whitney was a loner, even then. Any space around her was her personal space; just by existing, you were encroaching.

It was only after I sat down that I finally allowed myself to look again at the girl with the orange bikini. She had left the snack bar and was standing across the pool from us, her towel over one arm, a drink in her other hand, surveying the layout of benches and beach chairs.

"Here," Clarke said, handing over the deck of cards she was holding. "It's your deal."

Clarke had been my best friend since we were six years old. There were tons of kids in our neighborhood, but for some reason most of them were in their teens, like my sisters, or four and below, a result of the baby boom a couple of years previously. When Clarke's family moved from Washington, D.C., our moms met at a community-watch meeting. As soon as they realized we were the same age, they put us together, and we'd stayed that way ever since.

Clarke had been born in China, and the Reynoldses had adopted her when she was six months old. We were the same height, but that was about all we had in common. I was blonde-haired and blue-eyed, a typical Greene, while she had the darkest, shiniest hair I'd ever seen and eyes so brown they were almost black. While I was timid and too eager to please, Clarke was more serious, her tone, personality, and appearance all measured and thoughtful. I'd been modeling since before I could even remember, following my sisters before me; Clarke was a total tomboy, the best soccer player on our block, not to mention a whiz at cards, especially gin rummy, at which she'd been beating me all summer.

"Can I have a sip of your drink?" Clarke asked me. Then she sneezed. "It's hot out here."

I nodded, reaching down to get it for her. Clarke had bad allergies year-round, but in summer they hit fever pitch. She was usually either stuffed up, dripping, or blowing from April to October, and no amount of shots or pills seemed to work. I'd long ago grown used to her adenoidal voice, as well as the omnipresent pack of Kleenex in her pocket or hand.

There was an organized hierarchy to the seating at our pool: The lifeguards got the picnic tables near the snack bar, while the moms and little kids stuck by the shallow end and the baby (i.e., pee) pool. Clarke and I preferred the half-shaded area behind the kiddie slides, while the more popular high-school guys—like Chris Pennington, three years older than me and hands-down the most gorgeous guy in our neighborhood and, I thought then, possibly the world—hung out by the high dive. The prime spot was the stretch of chairs between the snack bar and lap lane, which was usually taken by the most popular high-school girls. This was where my oldest sister, Kirsten, was stretched out in a chaise, wearing a hot-pink bikini and fanning herself with a Glamour magazine.

Once I dealt out our cards, I was surprised to see the girl in orange walk over to where Kirsten was sitting, taking the chair next to her. Molly Clayton, Kirsten's best friend, who was on her other side, nudged her, then nodded at the girl. Kirsten looked up and over, then shrugged and lay back down, throwing her arm over her face.

"Annabel?" Clarke had already picked up her cards and was impatient to start beating me. "It's your draw."

"Oh," I said, turning back to face her. "Right."

The next afternoon, the girl was back, this time in a silver bathing suit. When I got there, she was already set up in the same chair my sister had been in the day before, her towel spread out, bottled water beside her, magazine in her lap. Clarke was at a tennis lesson, so I was alone when Kirsten and her friends arrived about an hour later. They came in loud as always, their shoes thwacking down the pavement. When they reached their usual spot and saw the girl sitting there, they slowed, then looked at one another. Molly Clayton looked annoyed, but Kirsten just moved about four chairs down and set up camp as always.

For the next few days, I watched as the new girl kept up her stubborn efforts to infiltrate my sister's group. What began as just taking a chair escalated, by day three, to following them to the snack bar. The next afternoon, she got in the water seconds after they did, staying just about a foot down the wall as they bobbed and talked, splashing one another. By the weekend, she was trailing behind them constantly, a living shadow.

It had to be annoying. I'd seen Molly shoot her a couple of nasty looks, and even Kirsten had asked her to back up, please, when she'd gotten a little too close in the deep end. But the girl didn't seem to care. If anything, she just stepped up her efforts more, as if it didn't matter what they were saying as long as they were talking to her, period.