The novel unfolds over the course of a single day inside a small nail salon, narrated by its owner, a Lao woman about to turn 42 who is known to her clients as Susan but whose real name is Ning. The story takes place almost entirely within the salon, called "Susan's," where every worker wears a name tag reading "Susan" to avoid replacing tags when staff turn over and to spare clients from mispronouncing their real names. All the workers share the same look: black shoulder-length hair and black clothes.
Ning opens the novel with a frank declaration about her profession: she looks at people's faces all day, and "everyone is ugly." She files, buffs, polishes, waxes, and threads. Though she sits below her clients, she is the one in charge, reading people through their physical details and the confessions they offer to someone they consider a stranger. She lives alone in a tiny apartment above the shop, unmarried and childless, a state she describes as chosen.
Before she was a nail technician, Ning was a boxer. Her father got her into the sport, and her coach, Murch, believed she could make it to the Olympics. She never won anything significant, and in one fight she put a girl in a coma, an incident Murch called "glorious" but that still haunts her. She aged out quickly and drifted through odd jobs until Murch connected her to Rachel, the sister of a man at the boxing gym, who owned a nail salon called Bird and Spa. Ning worked there for 12 years, learning everything about the trade, until Rachel pushed her out with cutting remarks about her age. Ning is also missing a finger on her left hand, a detail she references throughout the day but never fully explains. She found her current location five years ago, drawn to the park across the street where the winter trees reminded her of upside-down roots.
The day begins before the shop opens. Ning calls Mai, her most trusted worker, to review the schedule. Mai is blunt, assertive, and reliable, living across town with her mother and commuting 40 minutes by bus without complaint. Ning recognizes in Mai's temperament something of Murch. The day's appointments include a professional baseball pitcher booked under the alias "Derek Jeter" to keep his nail care secret from competitors, a waitress from a nearby restaurant, a bridal shower group, regulars named Marla and Janet, and a new client named Vanessa.
Also arriving is Noi, a 19-year-old new hire with no salon experience who has just had a baby by a married man. Ning trains her briskly, testing her at the wall of nail polish bottles, reprimanding her for wearing red polish (workers must keep their nails bare), and walking her through every protocol. When Noi asks about the salon's low Google rating, Ning dismisses it: Any dissatisfied client is offered a service for $10, and no one is ever permanently lost.
The pitcher enters with a quieter friend, pretending to rob the register with a hand-shaped gun under his shirt, a joke that terrifies Noi. Ning treats his nail injuries from gripping baseballs and talks him into eyebrow threading by fabricating a story about his brow telegraphing his curveball. When he makes his recurring joke about a "happy ending," the women discuss in their own language how they could hypothetically dismember him. Noi surprises everyone by enthusiastically joining in. At checkout, the pitcher tips the lowest amount possible.
As the day moves through clients, the novel builds a textured portrait of the salon's rhythms. The waitress Alyssa arrives to discuss online dating. While working on Alyssa's ring finger, the same finger Ning is missing, she massages the knuckle tenderly, quietly wishing a ring there. When Noi asks about a man named Bob whom Mai mentions, Ning reveals Bob is entirely fictional, a boyfriend she invents to deflect clients who cannot fathom a woman content alone. Noi says earnestly that she just wants people to have someone, and Mai tells Ning gently, "You're just afraid of love."
A bridal party of four women in matching white dresses arrives, and Ning panics because she cannot tell them apart. Nok, one of Ning's regular workers who has been missing shifts, fails to show again. Ning reflects on having advanced Nok months of pay after Nok's ex-partner stopped his support payments; Nok has not returned since. Annie, the standby worker, arrives quickly when called, and the Susans work the bridal party systematically, identifying each woman by physical markers.
Through the afternoon, Ning serves Marla, a regular who has had five miscarriages and watches strangers' baby videos on her phone, and Janet, a client who praises the competing Bird and Spa salon. During a lull, Ning invites a homeless man standing outside in for a free shave and pedicure. He accepts graciously, and when finished, remarks on her missing finger without asking what happened, simply acknowledging the absence.
Outside, Ning watches a pigeon get struck and killed by a car. She retrieves its body, and the dead bird triggers a vivid memory of knocking a girl to the floor in the ring, the girl not moving. She returns inside shaken and steadies herself by counting familiar objects: five chairs, four stations, centerpiece.
During a quiet moment, the Susans insist Ning sit in the centerpiece chair and pretend to be a client. Noi brushes Ning's hair and calls her pretty. Ning realizes no one has ever sincerely called her that before; she has been called tough, strong, and brave, but never pretty. She looks at the four of them in the mirror and acknowledges that without the shop and these women, she would feel she does not exist.
As the day winds down, the workers leave one by one. Noi pauses at the door, points to Ning's missing finger, and says she does not need to know what happened, that it is more interesting not to know. Alone, Ning fills the quiet with closing tasks. Looking out at passersby with cracked heels and untended nails, she feels a desperate urge to help them all, fantasizing about dragging the nail polish wall through the streets.
Then the lock jiggles. On the other side of the glass is Rachel, her former boss. Ning lets her in. Rachel surveys the shop and says only "Ten dollars," the secret pricing phrase, revealing she knows Ning's strategy. Ning tells her to pick a color. Rachel chooses a shade between lavender, pink, and pearl and sits along the wall. Working on Rachel's feet for the first time, Ning finds the intimacy startling. They work in silence, a quiet that feels complete rather than empty, because they know each other too well for talk.
Rachel pays with a $10 bill, cash that leaves no receipt, meaning she could deny the visit ever happened. As Ning reaches for the money, Rachel slides her hand along Ning's arm and gently touches the space where her missing finger was. She holds the small round bump with unexpected tenderness and gives Ning a kind smile, then walks out. Ning locks the door and stands at the window. She feels a warmth unfold inside her, like a tight coil coming undone. She touches the spot where Rachel held her finger. The shop fills with light, and she waits for the dark to come.