Julia Costell, a 27-year-old former ballet dancer, has returned to Harrington Arts Academy in Kansas City, the elite magnet school she once attended, as the middle school guidance counselor. Only seven weeks into the job, Julia is adjusting to a role she never planned for. Her dance career ended months earlier when she collapsed after years of secret bingeing and purging that nearly killed her. Now living with her parents in Overland Park during recovery, Julia endures constant parental monitoring. Her crisis runs deeper than the eating disorder: She learned at age seven that her dad is not her biological father, but the family has never discussed the subject, leaving Julia haunted by the fear that she is not truly loved.
Julia's routine shifts when Mrs. Morris, a rigid English teacher, brings her a personal essay by Dell Jordan, a 13-year-old foster child admitted to Harrington on the strength of extraordinary musical talent. Dell is half Choctaw, from rural Hindsville, Missouri, placed with foster parents Karen and James Sommerfield after her mother died of a drug overdose and her grandmother also passed away. In the essay, Dell describes a barefoot girl standing in a river, "drenched in light," wishing God would carry her away. Dell is terrified her foster parents will see the essay and discover she is not the perfect daughter she pretends to be. Julia returns the essay, encourages Dell to keep writing, and promises confidentiality. Mrs. Morris confronts Julia, declaring that both Dell and Julia herself, a former student who became a counselor rather than a performer, prove the school should remove those who lack excellence.
Julia's personal life grows more complicated when her mother announces that Julia's younger sister, Bethany, known as Bett, is getting married and is unexpectedly pregnant. The news deepens Julia's feelings of inadequacy. That evening, alone, Julia binges on ice cream and fights the urge to purge by remembering her doctor's warning that doing so again could be fatal.
Dell leaves a second essay in Julia's office on Say No to Drugs Day. She hides in the instrument storage room to avoid the drug assembly because it forces her to confront her mother's addiction and the question of whether she herself was born damaged by prenatal drug exposure. The essay describes Dell caring for her baby brother Angelo, her mother's boyfriend bringing drugs into the house, Angelo being given to his father, and her mother's departure before dying of an overdose. Dell wonders who her own father is and whether anything good can come from such origins.
Julia arranges daily tutoring sessions with Dell and begins reading
The Grapes of Wrath aloud with her to improve comprehension. She visits Jumpkids, an after-school arts program at Simmons-Haley Elementary, where she joins a dance class and finds herself falling into ballet positions, experiencing the joy of movement for the first time since her collapse. Julia meets Karen and James formally and observes the genuine love between Dell and her foster family. She learns that the school told Karen Dell's first-semester grades were satisfactory, when they are actually poor, placing Julia in an ethical bind between her promise of confidentiality and Karen's right to the truth.
Julia grows increasingly aware of a drug problem near Harrington. Shamika, a Jumpkids student, tells her that Harrington kids leave campus to buy drugs at taco stands on Division Street. Julia finds the claim credible when she observes suspicious traffic and what appears to be an undercover police operation nearby. At school, she questions Principal Stafford, who insists there has never been a drug problem and that drug-dog searches occur only on weekends when students are absent. Barry, Julia's good-natured office assistant, confirms that drug use is common knowledge among students.
Julia observes Cameron Ansler, the eighth-grade student council vice president and a school board member's son, arriving at school alternately hyperactive and drowsy depending on which parent he is staying with. She asks Stafford to have Cameron tested; Stafford refuses. An encounter with her ex-fiancé Jonathan and his pregnant new wife at a mall underscores Julia's sense of loss.
At a Jumpkids minicamp in Hindsville, Julia meets Keiler Bradford, a 26-year-old former foster kid adopted at 15 and a New York University biochemistry graduate who arrives on a Harley with a guitar on his back and a broken foot. Keiler is a brain tumor survivor who formerly used drugs recreationally and chose sobriety through self-commitment. He connects instantly with Dell and the other children through humor and authenticity. At Dell's invitation, Julia walks with Dell to her childhood home, a tiny, decaying house, and gains a visceral understanding of how far Dell has traveled. Julia recruits Keiler as a substitute algebra teacher at Harrington, and Barry begins studying with Dell, developing a friendship that draws her out of her isolation.
The crisis comes when Cameron has a public meltdown, crashing his head against his locker, slurring his words, and unable to stay lucid. Julia and Keiler intervene, but Mrs. Morris and the school nurse try to minimize the incident. Julia insists on calling both of Cameron's parents, overriding objections. When Stafford returns from sick leave, Cameron's mother has called the superintendent and is threatening a lawsuit. Stafford demands Julia apologize or face dismissal. Julia refuses.
Sent home to reconsider, Julia reads Dell's latest essay. Dell has learned from her caseworker, Twana Stevens, that the name Thomas Clay appears on her birth certificate as her father; social services must locate him or terminate his parental rights before the Sommerfields can adopt Dell, but he cannot be found. Dell reflects that knowing his name matters less than she expected, because she is finding happiness with her foster family. Karen has told Dell about losing a baby years ago and believing Dell was that daughter, arriving by a different path. Dell writes that sometimes at the breakfast table, she closes her eyes and feels "drenched in light from the inside out," transforming the lonely imagery of her first essay into belonging. Julia arrives at her own realization: She did not ruin herself through dance or her parents but through her own choices to hide and deny. She tells Stafford she will not apologize, will not resign, and intends to speak at the board meeting.
Julia's family attends the meeting in solidarity, along with Keiler. Julia uses her allotted time to describe the drug problem and the culture of denial that prioritizes the school's image over student safety. During her speech, Bett begins cramping, and the family rushes to the hospital. In the car, Julia finally asks her mother about her biological father. Her mother reveals he was a touring ballet dancer whom she briefly married, who died in a car accident when Julia was three, and who gave Julia the white jewelry box with the tiny ballerina that has sat on her dresser her entire life. At the hospital, Bethany and the baby are confirmed healthy.
Stafford fires Julia by voicemail. Keiler brings her personal items along with "Free Ms. C" notes from protesting students. He reports that Dell volunteered to read her essay about her mother's drug use aloud in English class, and that Mrs. Morris then arranged for Dell to read it at a school-wide assembly, where Dell dedicated it to Julia. Moved by Dell's reading, Cameron calls his father and confesses to his drug use. His father confronts Stafford, and the superintendent orders a drug-dog search that finds drugs in 15 middle school lockers.
At Bett's wedding, Dell sings with Keiler accompanying on guitar. Bett wears their mother's restored dress. Keiler tells Julia the board is likely to force Stafford into early retirement and offer Julia her job back. Julia watches Dell dancing freely, arms outstretched, transformed from the silent girl who once hid in a storage closet. Keiler invites Julia to dance, and she accepts. In the novel's closing moment, Julia steps into the light and feels drenched from the inside out, recognizing that her unexpected path has led her exactly where she was meant to be.