Olivia Shaw, a 38-year-old food magazine editor from San Francisco, has endured a devastating year: a car accident that shattered her right leg, the death of her elderly dog, the emotional absence of her fiancé Grant during her recovery, and the sudden death of her mother, Caroline Shaw, from pneumonia. While sorting through Caroline's papers, Olivia discovers correspondence from an English solicitor and learns that her mother was the long-missing daughter of the Shaw family, whose ancestral seat is the vast Elizabethan estate of Rosemere Priory. Caroline's brother, Roger Shaw, held the title of Earl of Rosemere before his disappearance. Caroline never spoke of her life in England before emigrating in her twenties. Olivia flies to England and is stunned to recognize the sprawling, vine-covered manor from the fantastical forest paintings her mother created for decades, scenes Olivia had always believed were imaginary.
Rosemere Priory, a Grade I-listed building (a designation meaning it cannot be altered or demolished without government approval), has been vacant for over 40 years, its rooms in various stages of ruin. Olivia's solicitor, Jonathan Haver, explains that inheritance taxes claim 40 percent of the estate's value and that restoration would cost a fortune. He mentions a strong offer from an unnamed buyer but provides few details, and Olivia senses he is not fully forthcoming.
In the nearby village of Saint Ives Cross, Olivia begins piecing together the life her mother concealed. Rebecca Poole, a horse breeder from the neighboring property, introduces her to Samir Malakar, a thatcher's journeyman whose grandmother was part of the Rosemere household. Samir guides Olivia through the manor, showing her a stained glass window salvaged from the estate's original abbey and a lavish bedroom belonging to her grandmother, Violet Shaw. There they find a photograph of their grandmothers together in India, and Olivia is startled to see her own features mirrored in Violet's face. She also meets Samir's sister, Pavi Malakar, who runs an Indian-fusion restaurant called Coriander, and their father, Harshad Malakar, who recalls playing with Caroline as a child at Rosemere. Harshad describes Violet as generous but volatile and shares a painful memory: his younger sister, Sanvi Malakar, vanished in 1975 and was never found.
George Barber, the Earl of Marswick, an elderly neighbor whose family has lived alongside the Shaws for centuries, warns Olivia that developers covet her land. He urges her to stay and protect the estate, offering to tutor her in the responsibilities of her position. Olivia also contacts Jocasta Edwards, a television host known as the Restoration Diva, who specializes in saving historic properties. Jocasta tours Rosemere and, despite the damage, is captivated by its stained glass, carved woodwork, and overgrown gardens. She notes that most of the house's original artwork and library are suspiciously absent. She agrees to feature the estate on her show, and Olivia reveals that her mother's California house has sold for over $3 million, providing funds to begin restoration. The plan calls for working south to north, starting with the roof.
Olivia breaks up with Grant, citing his emotional desertion during her hospitalization. He retaliates by suing for half the proceeds of her mother's house sale under community property rights and claiming her mother's paintings as a settlement, freezing the funds Olivia needs. Meanwhile, she settles into village life, renting a flat and planning the estate's first public picnic. Her connection to Samir deepens as she learns he was once a literature professor and published novelist whose marriage collapsed, and that he now writes popular science fiction under a pen name.
While exploring Violet's bedroom, Olivia and Samir find a key hidden behind a painting that references a book Olivia and her mother once shared. The key opens a wardrobe containing wrapped paintings and a box of photographs, including dozens of intimate images of Samir's grandmother, Nandini, taken over decades. The discovery confirms that Violet and Nandini were secret lovers for most of their lives. Olivia and Samir agree to keep the discovery private, moved by the decades of hidden love. In the aftermath, they acknowledge the attraction building between them and begin a relationship.
Crises multiply. Olivia's accountant discovers that Haver and the estate's caretakers have been draining the accounts for a decade, and Haver flees to Mallorca. Heavy rains cause part of the ballroom roof to collapse, and a skeleton found in the abbey ruins proves centuries old. Grant's lawsuit collapses after an art dealer produces photographs proving he was having an affair during Olivia's hospitalization, and the frozen proceeds from Caroline's house sale are finally released.
The first episode of Jocasta's show featuring Rosemere airs to great effect, and the estate's public picnic draws hundreds of villagers. At the event, Alexander Barber, the earl's nephew, privately presents Olivia with a substantial offer to buy the estate and warns her about parties plotting to develop her land. Samir's mother, visiting from India, privately tells Olivia she is too old for her son and that he needs someone who can give him children. The words cut deep but do not diminish Olivia's feelings.
The Earl of Marswick dies of a heart attack. On his deathbed, he makes Olivia promise to save Rosemere. Shortly after, fire breaks out in the main house. Tenants form a bucket brigade, and a sudden rainstorm helps extinguish the blaze, but the south end suffers serious damage. The next day, a landslide in the rose garden uncovers two sets of human remains beneath the giant orange-and-peach rose that Caroline painted obsessively. One is identified as Sanvi Malakar; the other is believed to be Roger Shaw.
Harshad reveals a secret he has carried since 1977. Roger killed Sanvi and was burning her body when Caroline discovered him. Caroline stabbed Roger to death with gardening shears and came to Harshad for help. Together they buried both bodies in the rose garden and planted roses over the graves. Roger had also discovered Violet and Nandini's love affair and used it as blackmail, forcing Violet into a marriage that destroyed both women's lives. Harshad confirms that Caroline was pregnant when she left England, meaning Olivia is at least a year older than she believed. Roger was not her father, but Harshad does not know who was. Olivia grieves fully for the first time, weeping for her mother, for Violet and Nandini, for Sanvi, and for the decades of silence Caroline endured.
Olivia walks through the damaged house alone, confronting her fear room by room. From the tower, she spots a rainbow over a field of golden rapeseed. The image triggers the final connection in her mother's treasure hunt: a rainbow painting from Olivia's childhood bedroom bears an address on its back, and a key left for her by the earl opens a storage unit north of London. Inside, Olivia and Samir find all the missing books from Rosemere's library, dozens of paintings, and Caroline's final work: a large canvas of a warmly lit cottage with a mother and child visible through the window. Olivia understands that Caroline, who knew she was dying of cancer, set up the treasure hunt to give her daughter purpose and lead her to her heritage. The stored artworks and books can fund continued restoration. Olivia decides to stay, envisioning a destination restaurant and organic farm market drawing on her food expertise. The novel closes as she and Samir affirm their love and commit to building a future together at Rosemere.