Sixteen: Never Trust An Invite Without A Return Address.

"So are you coming over tonight?" Hanna switched her BlackBerry to her other ear and waited for Sean's answer.

It was Thursday after school. She and Mona had just met for a quick cappuccino on campus, but Mona had to leave early to practice her drive for the mother/daughter golf tournament she was competing in this weekend. Now, Hanna sat on the front porch, talking to Sean and watching the six-year-old twins next door draw surprisingly anatomically correct naked boys in chalk all over their driveway.

"I can't," Sean answered. "I'm really sorry."

"But Thursday is Nerve night; you know that!"

Hanna and Sean were hooked on this reality show Nerve, which documented the lives of four couples who'd met online. Tonight's episode was extremely important, because their favorite two characters, Nate and Fiona, were about to do it. Hanna thought it might at least start a conversation.

"I…I have a meeting tonight."

"A meeting for what?"

"Um…V Club."

Hanna's mouth fell open. V Club? As in Virginity Club? "Can you skip it?"

He was quiet for a minute. "I can't."

"Well, are you at least coming to Noel's tomorrow?"

Another pause. "I don't know."

"Sean! You have to!" Her voice squeaked.

"All right," he answered. "I guess Noel would be kinda pissed if I didn't."

"I would be pissed too," Hanna added.

"I know. See you tomorrow."

"Sean, wait—" Hanna started. But he'd already hung up.

Hanna unlocked her house. Sean had to come to the party tomorrow. She'd hatched a foolproof, romantic plan: She'd taken him to Noel's woods, they'd confess their love for each other, and then they'd have sex. V Club couldn't argue with having sex if you were in love, could it? Besides, the Kahn woods were legendary. They were known as the Manhood Woods, because so many guys at so many Kahn parties had lost their virginity there. It was rumored that the trees whispered sex secrets to new recruits.

She stopped at the mirror in the hallway and pulled up her shirt to examine her taut stomach muscles. She swiveled sideways to investigate her, round butt. Then she bent forward to look at her skin. Yesterday's blotchiness was gone. She bred her teeth. One bottom front tooth crossed over a canine. Had they always been that way?

She threw her thick-strapped, gold leather handbag onto the kitchen table and opened the freeze. Her mom didn't buy Ben & Jerry's, so Tofutti Cutie 50-percent-less sugar faux ice-cream sandwiches would have to do. She took out three and began to greedily unwrap the first one. As she took a bite, she felt that familiar tug to eat more.

"Here, Hanna, have another profiterole," Ali said had whispered to her that day they visited her dad in Annapolis. Then Ali turned to Kate, her dad's girlfriend's daughter, and said, "Hanna's so lucky—she can eat anything and not gain an ounce!"

It wasn't true, of course. That's what made it so mean. Hanna was already chubby and seemed to be getting more so. Kate giggled, and Ali—who was supposed to be on Hanna's side—laughed too.

"I got you something."

Hanna jumped. Her mom sat at the little telephone table in a hot pink Champion sports bra and black flared-leg yoga pants. "Oh," Hanna said quietly.

Ms. Marin appraised Hanna, her eyes settling on the ice-cream sandwiches in her hands. "Do you really need three?"

Hanna looked down. She'd comped through one sandwich in less than ten seconds, hardly even tasting it, and had already unwrapped the next.

She smiled faintly at her mom and quickly stuffed the remaining Cuties back into the freezer. When she turned back around, her mother set a little blue Tiffany bag on the table. Hanna looked at it questioningly. "This?"

"Open it."

Inside was a little blue Tiffany box, and inside that was the complete Tiffany toggle set—the charm bracelet, round silver earrings, plus the necklace. The very same kind she'd had to hand over to the Tiffany's woman at the police station. Hanna held them up, letting them sparkle in the overhead light. "Wow."

Ms. Marin shrugged. "You're welcome." Then, to signify that the conversation, she retreated to the den, unrolled her purple toga mat, and turned on her Power Yoga DVD.

Hanna slowly slid the earrings back in the bag, confused. Her mom was so weird. That was when she noticed a creamy, square card envelope sitting on the little telephone table. Hanna's name and address were typewritten in all caps. She smiled. An invite to a sweet party was just the thing she needed to cheer up.

Breathe in through your nose, out through your mouth, the soothing yogi instructed from the TV in the den. Ms. Marin stood with her arms placidly by her sides. She didn't even move when her BlackBerry started singing Flight of the Bumblebee, which meant she had an e-mail. This was her Me time.

Hanna grabbed the envelope and climbed upstairs to her room. She sat down on her four-poster bed, felt the edges of her billion-thread-count sheets, and smiled at Dot, sleeping peacefully on his doggie bed.

"Come here, Dot," she whispered. He stretched and sleepily climbed into her arms. Hanna sighed. Maybe she just had PMS, and these jittery, uneasy, the-world-is-caving-in feelings would go away in a few days.

She sliced the envelope open with her fingernail and frowned. It wasn't an invitation, and the note didn't really make sense.

Hanna,

Even Daddy doesn't love you best! —A

What was that supposed to mean? But when she unfolded the accompanying page stuffed inside the envelope, she yelped.

It was a color printout from a private school's online newsletter. Hanna looked t the familiar people in the photo. The caption said, Kate Randall was Banbury School's student speaker at the benefit. Pictured here with her mother, Isabel Randall, and Ms. Randall's fiance, To Marin.

Hanna blinked quickly. Her father looked the same as when she'd last seen him. And although her heart stopped when she read the word fiance—when had that happened?—it was the image of Kate that made her skin itch. Kate looked more perfect than ever. Her skin was glowing and her hair was perfect. She had her arms gleefully wrapped around her mom and Mr. Marin.

Hanna would never forget the moment she first saw Kate. Ali and Hanna had just gotten off Amtrak in Annapolis, and at first Hanna saw only her dad leaning up against the hood of his car. But then the car door opened, and Kate stepped out. Her long chestnut hair was straight and shiny, and she held herself like the kind of girl who'd taken ballet since she was two. Hanna's first instinct was to crouch behind a pole. She looked at her snug jeans and stretched-out cashmere sweater and tried not to hyperventilate. This was why Dad left, she thought. He wanted a daughter who wouldn't embarrass him.

"Oh my God," Hanna whispered, searching the envelope for a return address. Nothing. Something occurred to her. The only person who really knew about Kate was Alison. Her eyes moved to the A on the note.

The Tofutti Cutie burbled in her stomach. She ran for the bathroom and grabbed the extra toothbrush in the ceramic cup next to the sink. Then she knelt down over the toilet and waited. Tears dotted the corners of her eyes. Don't start this again, she told herself, gripping the toothbrush hard by her side. You're better than this.

Hanna stood up and stared in the mirror. Her face was flushed, her hair was strewn around her face, and her eyes were red and puffy. Slowly, she put the toothbrush back in the cup.

"I'm Hanna and I'm fabulous," she said to her reflection.

But it didn't sound convincing. Not at all.