Three generations of midwives in Providence, Rhode Island, each harbor secrets that threaten to reshape their family. The novel alternates among Neva Bradley, a 29-year-old certified nurse-midwife at St. Mary's Birthing Center; her mother, Grace, a passionate home-birth midwife; and her grandmother, Floss, a retired midwife in her eighties. Interspersed with the present-day story are Floss's flashbacks to 1950s England, where the origins of the family's deepest secret gradually come to light.
Neva, quiet and fiercely private, has been hiding her pregnancy for months. At a birthday dinner on Conanicut Island, a spilled water pitcher soaks her shirt and reveals her belly. Neva admits she is 30 weeks along but refuses to name the father. Grace, exuberant and boundary-crossing, is frustrated by her daughter's secrecy and tells her husband, Robert, an accountant facing potential layoffs.
Grace's investigation leads her to sneak into Neva's client file at the birthing center, where the father's name field is blank. She confronts Neva at the hospital, suggesting rape and then guessing the man is married; Neva denies both. Grace notices chemistry between Neva and Dr. Sean Cleary, a married obstetrician-gynecologist, and concludes the father must be a doctor, a profession Grace disdains for its interventionist approach to birth.
Floss lies awake at night, haunted by parallels to her own past. She has told her family for decades that Grace's father was a farmer killed in a tractor accident and that she emigrated alone from England with her newborn. Her partner of eight years, Lil, senses Floss is concealing something far larger.
Floss's flashbacks unfold in stages. In Watford, England, in 1953, she met Bill McGrady, a charming man who married her fellow midwife and close friend, Elizabeth. Over the following months, Elizabeth grew visibly thinner despite being pregnant. When Floss visited, she discovered a large bruise covering Elizabeth's torso. Elizabeth claimed she fell but begged Floss not to tell anyone.
In the present, Patrick, a pediatrician who has been crashing on Neva's couch since his divorce, discovers her pregnancy. Their friendship dates back to a trivia night where Neva first felt attracted to him but learned he was engaged. She has kept her feelings buried ever since.
When Grace's client Gillian goes into early labor, Grace calls Neva to assist. During examinations, both women feel hard bone and a gap in the baby's mouth, a face presentation—a birth position in which the baby's face, rather than the crown of its head, presents first in the birth canal—suggesting a cleft palate. Neva calls Patrick, who drives through a storm to help. Grace delivers the baby, who has a cleft lip and palate but is otherwise healthy. A doctor at Newport Hospital files a complaint, and Grace's license is suspended. Robert is furious, already anxious about his own potential layoff. Grace defies the suspension and secretly delivers babies for cash.
At the hospital, a gossipy nurse named Marion announces Neva's pregnancy during a cesarean delivery (C-section). Afterward, Sean pulls Neva aside and anxiously asks about her dates, fearing he might be the baby's father. Neva assures him the baby is not his, and he is visibly relieved.
Patrick takes Neva to dinner and offers to tell people he is the baby's father, sparing her from questions. Outside the restaurant, he takes her hand in front of the chief obstetrics resident, letting the assumption stand. That evening, Floss is hospitalized with a minor heart attack. At her bedside, Grace notices Floss's blood type is AB positive, a detail that could raise questions about Grace's true parentage. After driving Neva home, Patrick kisses her, revealing genuine feelings. They agree to tell colleagues Patrick is the father, though Neva refuses to lie to Grace and Floss.
Patrick discovers during a routine check that Neva's baby is breech, meaning the baby is positioned feet- or buttocks-first rather than headfirst. Neva is devastated, facing the likelihood of a C-section rather than the natural birth she has championed for her clients.
Floss's flashbacks reach their climax. When Elizabeth went into labor, Floss and their midwife friend Evie found her gaunt and malnourished. Elizabeth admitted Bill withheld food when he was displeased. Floss discovered the kitchen larder padlocked and broke it open, finding it full of provisions. Elizabeth delivered a baby girl she named Grace but began hemorrhaging shortly after and died. Floss took the baby and told Bill the infant had died too. Evie falsified the birth certificate to list Floss as the mother, and Floss fled to her parents' home before booking passage to America. Bill was later charged with drowning the baby but never convicted.
Marion spreads a rumor at the hospital that Neva is having an affair with Sean. In a stairwell, Sean inadvertently reveals details of the drunken night they slept together, when Neva comforted him after his wife, Laura, was diagnosed with a brain tumor. Patrick overhears from the landing below, confronts Neva, and walks away when she confirms the truth.
Neva confides in Robert, who consoles her. Grace overhears and walks for hours through the snow, reflecting on how she has spent years expecting Neva to fill the void left by her own absent father. She arrives at Floss's house, where Neva is already there. For the first time, Grace simply holds her daughter and offers comfort without pressing for answers. Then Neva's water breaks.
The only road off the island is closed by the blizzard. Grace calls an ambulance, but dispatch warns a helicopter may not arrive in time. The delivery turns out to be a footling breech, with one foot emerging first. Grace panics, but Floss calmly guides her through every step. After tense maneuvers to free the shoulders and engage the head, Grace places a healthy, crying baby girl into Neva's arms.
Neva wakes at St. Mary's Hospital to find Patrick at her bedside. The baby appears full-term, meaning the dates were wrong and Sean cannot be the father. Neva realizes the father is Mark, an accountant she went on a single date with before her night with Sean. Grace asks why Neva kept the secret. Neva explains she feared sharing the truth would mean losing control of her experience. Grace responds with pride, and Neva addresses her as Mom for the first time in years.
In the hospital family lounge, Floss tells Grace the full truth: Grace is not Floss's biological daughter but the child of Elizabeth, who died because Bill's abuse and starvation left her too weak to survive childbirth. Grace asks if she resembles Bill. Floss tells her she is like Elizabeth in her looks, personality, and love of midwifery. Rather than wanting to investigate her biological origins, Grace says she considers Floss her true mother.
Mark visits the hospital and is shocked to learn the baby is his. He says she looks like his recently deceased mother, Mietta. Neva names the baby Mietta Grace, after both grandmothers. Grace receives a letter restoring her midwifery license. Robert reveals he has been laid off but is at peace. Grace invites Lil into the family, declaring no more secrets. Patrick gives Neva a baby book listing himself as the baby's father, offering to share the role with Mark. They reconcile, acknowledging their love. The novel closes as Neva, Patrick, and Mietta walk together toward Nellie's, the three generations forming an expanded, unconventional, but loving family.