Before she’d wrapped the gun up in the scarf, she’d picked it up and held it next to her cheek, stroking herself, the way villains were always caressing women in spy movies. It didn’t look the same. Maybe it was because she didn’t have the right kind of face. Her mother always told her that her face was heart-shaped, but all she saw was that it was sharp in an almost witchy way-pointy chin, hollow cheeks. When an actor traced a line down an actress’s face, the gesture was sexual and violent at the same time, or so Ms. Cunningham had said in her “Rhetoric of Images” class. She told the girls they had to learn to recognize such images and decode them, so they wouldn’t be infected by them. It made no sense, though. She couldn’t get why the gesture was sexual if it denoted rape, which everyone kept insisting wasn’t about sex but violence. Because the gun is a phallic symbol, Ms. Cunningham explained. Rape is an act of violence that happens to be expressed through sex. “But you also said rape isn’t about sex, that if boys force us to do anything we don’t want to do, it’s the same as assault.” Yes, and films confuse the message, suggesting that rape can be sexual, when it clearly isn’t, setting you up to make poor choices. Don’t you see?

She was beginning to. She now saw how ideas that might appear to be at the opposite ends of a spectrum were really matched sets, yin and yang, eternally connected rings. No love without hate. No peace without war. “We had to destroy the village in order to save it.” Mr. Blum, the history teacher, was always offering this as an example of the idiotic things said during the Vietnam War, that war being his big reference point, the proof that he had once cared about something larger than himself and his precious little sports car, which he buffed with a chamois cloth in good weather, out in the teachers’ parking lot. It seemed silly to be so proud of a car, when half the kids at Glendale drove nicer ones. You have to destroy the village in order to save it. She no longer saw the paradox. Sometimes you do have to destroy things, even people, in order to save them.

Yet these thoughts, while appropriately deep, did not figure into her last words. She had only so much time, so much space, and she was undeniably self-conscious, perhaps a bit too fixated on the effect of what she was doing. The letter she composed was factual, yet somehow false. Even her handwriting was false-florid, overdone, so she couldn’t fit it all onto one sheet of paper as she had planned. She had lost the habit of expressing herself honestly, without irony and grandiose turns of phrase. She wrote about heaven and love, and called on old loyalties. She asked only that the truth be told. She wrote it just that way, in just those words: “I ask only that the truth be told.”

After much chewing on the end of her pen, a bad habit she had never outgrown even though it often left her with blue lips, she crossed out the word “only.” She knew that it was a lot to ask, perhaps the most a person can ask, under certain circumstances.

When the shooting started, Alexa Cunningham was looking at Anita Whitehead’s arms-her arms, then her underarms, because Anita threw her hands over her head and began to shriek. Later Alexa Cunningham would try to rewrite that memory in her head, replace it with something more portentous, but the image was stubborn: Anita’s tremulous upper arms bursting into hives, then the tiny white mothballs of roll-on deodorant visible in the stubble of her underarms just before she threw the telephone down. Alexa even caught a whiff of something floral, antiperspirant or perfume, and found time to wonder why someone who claimed to suffer from multiple chemical sensitivities would use anything scented.

That troubled her, too-how one track of her mind detached, finding room for trivial observations in the midst of a crisis. Later she told herself that it was simply a citizen’s duty to be prepared for the role of eyewitness, absorbing every detail of an unfolding tragedy, and one could not pick and choose what one noticed. Still, there was no getting around it-what Alexa saw, at the moment that everything changed, was Anita’s arms, swaying like poorly staked hammocks; Anita’s lips, puckered around the straw in her omnipresent Diet Vanilla Coke, then rounding into a scream; and Anita’s eyebrows, too overplucked to register surprise. And what Alexa heard was a voice in her head, coolly narrating events. Why was that? Where did such a voice come from? But Alexa knew. If you lived to tell the story, then you lived. She had instinctively thought like a survivor, and there could be no shame in that.

When the shots came, I was picking up my mail in the office and listening to Anita complain about her imaginary symptoms.

“TGIF,” Anita had said a few minutes earlier by way of greeting. “Tee-Gee-Eye-Eff.”

“Hmmm,” Alexa murmured, eyes on her mail so she would not stare at Anita’s arms, left bare by a sleeveless knit top. Alexa’s older brother, Evan, had once dressed as a woman for Halloween, donning a flesh-colored turtleneck beneath a muumuu, then stuffing the arms with tennis balls so they wobbled back and forth just the way Anita’s arms shook whenever she moved them. Alexa, eight at the time, had laughed until she almost wet herself. Evan was imitating their own mother, who was a good sport about such things.

“You got big plans for the weekend, Lexy?”

Alexa had never been known by this nickname, which sounded a little soap-operaish to her ear.

“Uh-uh. You know how the work floods in, the last week for seniors. Have to make sure all my kids are ready to walk next Thursday.”

“Supposed to be beautiful this weekend. I wish I could go somewhere. But even if we could get down the ocean”-she gave it the local pronunciation, downy eauchin-“my doctor says I really shouldn’t.”

“Hmmmm.”

“Because of the sun.”

Alexa made no reply, pretending absorption in Barbara Paulson’s memo on senior pranks. Faculty and staff were to be reminded-that was her wording, were to be reminded-that any student participating in a stunt involving damage to property, no matter how small, would be banned from the graduation ceremony. As a relatively new school, Glendale did not have many entrenched traditions, but outgoing seniors did have a curious habit of setting off firecrackers in the woods just beyond the athletic fields. We also take a strict view of injury, Barbara had added, making bodily injury seem an afterthought to the more serious problem of vandalism. The memo was pure Barbara-bureaucratic, poorly written, unintentionally funny. But then Barbara was never funny on purpose.

“And the air.” Aaaaaah-er in Anita’s accent. “The very air makes my skin sting. My doctor says it’s because of the salt in the breeze.”

“Hmmmmm.”

Anita’s doctor was a topic to be avoided at all costs. Six months ago Anita had decided that her health problems-not only her hives but the headaches and chronic shortness of breath-were the fault of some toxin in the Glendale High School heating and cooling ducts. Or the carpet. Or the sealant used on the gymnasium floor. Three tests had been ordered so far, and three tests had come back with inconclusive results. Yet Anita was still threatening legal action, and when she tired of speaking of her doctor, she mulled out loud about which lawyer might represent her. All her options advertised on local television, although she sometimes glimpsed someone promising on Court TV. Otherwise she was waffling between the “Let’s talk about it” guy and the firm endorsed by former Baltimore Colt Bubba Smith. Alexa, one of the few faculty members who accepted multiple chemical sensitivity as a legitimate medical condition, did not scoff at the science behind Anita’s claim. She just didn’t happen to believe that Anita suffered from anything other than her own bad choices.