Written in verse, this novel is structured as a series of letters and poems addressed to an unnamed "Dear Sir," whose identity is not revealed until the final pages. The narrator is Bea Coughlin, a wheelchair user with cerebral palsy, a condition affecting movement and coordination, who attends Cedar Crest Presbyterian, a small private school that doubles as a church. Bea opens by recalling the spring Monday when she heard popping sounds during English class and mistook them for fireworks. She had been researching magic tricks for Josie, her "Little," a shy kindergartener paired with her through the school's buddy system. When the sounds turned out to be gunshots and everyone ran, Bea could not. She insists on telling the full story from the beginning, asking the reader to pay attention.
In Part One, "Seek," Bea recounts the ten ordinary days before the shooting. She lives with Max, her guardian and the school nurse, who nursed Bea in the neonatal intensive care unit (NICU) when Bea was born premature. Max became Bea's foster mother and brought her home on Easter Sunday, naming her Beatrix after Beatrix Potter. Their shared promise, "Xs to Xs," a play on the X in both Beatrix and Maxine, is their sacred vow. Bea's world is small and warm: Lucy, their neighbor and a construction worker who built Bea's wheelchair ramp, and Lucy's husband, Aaron, who works at an independent bookstore, complete their chosen family.
At school, Bea doodles gnomes on her desk during testing instead of answering questions. Her English teacher, Mrs. Canelli, redirects her and gives her a blue notebook labeled "For Your Art." Bea coaxes Josie from her shell with Bubble Tape gum and comforts her during an Easter egg hunt when Josie hides behind a bush. On weekends, Bea watches videos of street magicians and resolves to learn a card trick for Josie.
In Part Two, "Hide," Bea and Max arrive late on a Monday. Bea attempts a card trick for Josie at drop-off but guesses the wrong card, promising to try again at lunch. During a test in Mrs. Canelli's classroom, popping sounds begin. The alarm screams. Mrs. Canelli shouts for everyone to get down and runs for the door with her keys. The door explodes in smoke and glass. Bea, her wheels locked, freezes. She cannot get down from her chair. When she ends up on the floor, glass covers the ground and desks lie overturned. Near the ruined door, she sees a silver Birkenstock, Mrs. Canelli's shoe, and shuts her eyes.
Police declare the room secure. Officer Ramos frees Bea's leg brace from her footrest and lifts her into her chair. He pushes her to the elevator while the rest of the class takes the stairs, deepening her isolation. Bea screams that her mother works in the building, but Officer Ramos redirects her to a side exit and an accessible bus headed for a reunification site. Bea watches other families reunite while Max does not appear. Finally, Max's voice screams Bea's name across the sanctuary. They collide and cling to each other.
Part Three, "Heal," follows Bea through the weeks after the shooting. She cannot sleep in her bedroom because the enclosed space triggers panic; she cannot escape on her own. Lucy brings a trundle bed to the screened-in porch, and Bea sleeps outside. The next morning, she spots a dropped pack of cards and panics, remembering she forgot about Josie in the chaos. Max assures her Josie is safe, then shows Bea the list of victims: three young students, the school custodian, and Mrs. Canelli. Bea already suspected Mrs. Canelli was gone after seeing her shoe, but reading the name makes it final. She remembers Mrs. Canelli's pink wedding dress and her
Charlotte's Web phone case. Unable to eat when the dead cannot, Bea retreats to the porch.
Bea refuses to attend a gun control protest, declines counseling, and stops answering calls from Rani, her classmate. At a hospital reunion picnic, a piñata bursts with a bang and triggers a flashback. On Easter, the family holds their annual rubber duck fishing tradition at home since the school building remains closed. Max presses Bea to see a counselor. When Bea refuses, Max asks how she feels about horses.
Max explains equine therapy, therapeutic horseback riding beneficial for both trauma and cerebral palsy. Bea agrees to try if she does not have to talk. At Innisfree Equestrian Therapy, the owner and instructor, Trina, starts Bea with grooming. Bea uses a curry comb on Dumpling, a short white horse who leans into her touch, and something inside her loosens. On a later visit, she transfers onto Dumpling's back and rides for the first time, her hips swaying in a motion that mimics walking. Trina shares that her son Charlie has spina bifida and has been riding since childhood. In later sessions, Bea steers through cones, navigates a woodland Sensory Trail, and practices letting go of the reins.
Part Four, "Hope," opens with a letter in which Bea mentions seeing the recipient in a photograph on a horse beside a red barn and an American flag. During one lesson, a thunderclap triggers a flashback. Bea covers her ears and falls from Dumpling, unable to do anything she has been trained to do. She curls up in the dirt, devastated that her one safe place has been ruined.
Afterward, Bea confesses to Max what has haunted her: She did not get down when Mrs. Canelli told her to. She froze, and she is sorry. Max tells Bea through tears that she did nothing wrong, that a child should not have to protect herself from this, and that they will fight together so it never happens again. Bea lies awake thinking about Max's words and Mrs. Canelli's favorite saying: "Nothing changes if nothing changes." She wonders what she, a kid in a wheelchair, can possibly do.
Days later, Bea finds her untouched backpack from the shooting and discovers the blue notebook Mrs. Canelli gave her. She begins to write, not drawings but words, about cherry picking, card tricks, smoke, a silver shoe, crunching glass, and mothers crying. She is emptied out but filled with purpose. For the first time since the shooting, she sleeps through the night. She returns to Innisfree, grooms Dumpling, and whispers, "Thank you for being my Buddy." She agrees to attend the school's reopening ceremony.
At the ceremony, Bea freezes in the parking lot and is about to flee when Josie appears at the edge of the lawn. Josie asks Bea to sit with her. Bea pulls back her hood, revealing hair freshly dyed lemon yellow and electric blue, the colors of Cedar Crest and Innisfree. During the prayer, Josie whispers that she likes Bea's hair. When they look up, the clouds have cleared to reveal a full rainbow. The band plays "Somewhere Over the Rainbow." Bea slips Josie a piece of gum, and they watch the sky together.
The novel closes with a final letter in which Bea reveals her recipient: "Mr. Governor." She thanks him for praying for the city and reading the names of the victims but says prayer is not enough. She argues that if the government can mandate accessible sidewalks, chirping stoplights, and bus lifts so people with disabilities have equal opportunity to participate in the world, then it can ensure they also have equal opportunity to survive. She signs the letter "Sincerely yours, Bea Coughlin," asking the governor to pay attention and then act.