The narrator, Sally Holt, addresses her older sister, Kathy Holt, stating: “You disappeared on a school night” (3). Writing to Kathy after her death, Sally recalls their shared childhood in suburban Connecticut through a series of flashbacks. She remembers their nightly routine of laying out school clothes in the bedroom they shared, where their names are spelled in glow-in-the-dark stars on the ceiling—a compromise after Kathy insisted the ceiling could never be the sky. An old, dying maple tree, rumored to have been planted by Puritans, sits outside their window. Their father, Richard, is a safety-conscious consultant for telephone tower workers, while their mother, Susan, is a former teacher and community leader whose high school boyfriend was killed in the Vietnam War. She met Richard at that boyfriend’s funeral.

The flashbacks trace Kathy’s long-standing infatuation with Billy Barnes, the son of a local florist. The crush begins when Kathy (fourth grade) is paired to dance the “Football Tango” with Billy (fifth grade) for a Thanksgiving celebration, and he compliments her hair. Kathy begins collecting facts about him, learning that his father, Bill, once broke his neck falling from a ladder. The sisters visit Billy’s father’s shop, Bill’s Tree and Garden, taking rose petals as mementos. After his father’s accident, Billy becomes known for performing dangerous stunts. In one instance, he jumps off the school roof on a dare, breaking his leg and getting knocked unconscious. While classmates line up to sign his cast, a girl named Priscilla writes her phone number on it, making Kathy jealous. At a school event, Kathy dresses as Annie Oakley and Sally as Florence Nightingale. Billy briefly speaks to them, admiring Kathy’s toy gun.

Years later, in middle school, Kathy is thrilled when Billy holds a door open for her. Sally, who’s in fifth grade, has a brief, non-verbal relationship with a classmate, Peter Heart, which ends after she beats him in the class spelling bee. Their grandmother often compares Kathy’s beauty to Sally’s intelligence, predicting Sally will become a nun. As a high school sophomore, Kathy is chosen to sing the National Anthem at a basketball game. Billy plays poorly, and he later confides in Sally that he was distracted because he fell in love with Kathy at that very moment.

In seventh grade, after watching a talk show about a woman with two vaginas, Sally asks a question about it at a school health assembly, which leads to widespread ridicule. The phrase “SALLY HOLT HAS TWO VAGINAS” is written on a bathroom stall (21), and Sally becomes shy and withdrawn, prompting her mother to buy a book titled The Shy Child. During a family summer vacation to Watch Hill, Rhode Island, the sisters see Billy at a gas station mini-mart with his girlfriend, Shelby Meyers. Later that summer, when the family’s air conditioner breaks, their father refuses to fix it, lecturing them on toughness. Their mother takes the sisters to the town pool, where Billy works at the snack bar. He winks at Kathy when she buys a snack, and Kathy later calls the flirty lifeguard, Lisa Halloway, a “slut.” The sisters take a personality quiz that identifies Kathy as a spontaneous “Green Person” and Sally as a structured “Red Person.” To prove she can be daring, Sally climbs the high dive, loses her balance, falls, and is knocked unconscious. Billy rescues her from the pool and performs CPR to revive her.

As a thank-you, Susan invites Billy to dinner. Afterward, Kathy walks him to his car, where he asks for permission to kiss her. They become a couple, spending their summer together at the pool. Later, during a hurricane, the family bonds while playing Scrabble. The next day, Richard inspects the storm damage and declares the old maple tree is “not a survivor” (55).

During Kathy’s junior year, Billy begins driving her to school. On one ride, he and Sally discuss the Greek myth of Philomela. Sally faces increasing harassment on the school bus, where a boy named Rick Stevenson and his friends hold her down and try to lift her shirt, referencing the two-vaginas rumor. Feeling distant from Kathy, who is absorbed in her relationship with Billy and shares explicit details about her sexual experiences, Sally decides not to tell her about the bullying. Sally attempts to run away by hiding in the back of her mother’s van. Her mother finds her after driving to the mall while crying and listening to a self-help tape. After Sally confesses to running away, her mother comforts her and impulsively orders a white couch from Macy’s, which will not be delivered for months. In the present timeline, Sally notes that by the time the couch arrived, Kathy would be dead.

Six weeks after the incident at the mall, Kathy prepares to go with Billy to his semifinal basketball game. She asks Sally to secretly take notes on the President’s State of the Union address for a history quiz the next day. While watching the speech with her parents, Sally feels shocked when her mother tells her father she wants to “fuck the president.” Sally writes “MOM WANTS TO FUCK THE PRESIDENT” in Kathy’s history notebook (78). The next morning, Sally withholds the notes, demanding a ride to school from Billy. In the car, Kathy finds Sally’s note and laughs, showing it to Billy. As he looks away from the road to read the notebook, a deer runs in front of the car. Billy swerves and crashes the car into a tree. The last word Kathy says is Billy’s name.