The narrative flashes back to 1987, when Evelyn was a trainee at the British Museum and happily in a relationship with her colleague, Asa. He invites her to a formal lunch at Rules restaurant to discuss their future, and she expects him to ask her to move in with him. On her way to the restroom, Evelyn is horrified to see her father, Edwin, having an illicit lunch with her landlady, Frances Parfait; she witnesses him kissing Frances’s hand while his other hand pushes her tweed skirt up her thigh. Shocked and physically ill, Evelyn flees the restaurant, abandoning Asa. 

She rushes back to the museum, arriving just in time for a ceremony unveiling newly restored Egyptian artifacts. Her supervisor, Dr. Marianne Guest, calls her to the front and shakes her hand. The motion, combined with alcohol from her lunch with Asa and shock from seeing her father, causes Evelyn to vomit, knocking over and destroying three precious ancient pots. A fourth, a grain jar, survives but is the least rare of the pieces.

Evelyn’s furious father collects her from the museum. On the train home, somewhere between Exeter and Newton Abbot, she confronts him about seeing him with Frances Parfait. Edwin slams his hand on the table and denies it, insisting she was mistaken and warning her not to make such accusations. Overwhelmed by shame from the museum disaster, Evelyn accepts his lie. Back home, she sinks into a depression, ignoring calls and a letter from a heartbroken Asa. Her family establishes the local museum to give her a purpose. 

The narrative returns to the present, where Evelyn lies in the museum’s diorama bed. Having re-evaluated her father’s credibility after the encounter with Edie, she speculates that her birth mother might not have been Cornish at all, but someone from her father’s life in London, possibly Frances Parfait.

Evelyn is too depressed to perform her daily beach-comb for objects. She thinks of her mother, who abandoned her degree to marry Edwin to her family’s confusion. She considers her brief interactions with Frances Parfait, having considered her friendly but too career-oriented for motherhood.

The next morning, Sariah visits Evelyn at the museum. She reports that their campaign is having an effect on the council and also mentions that her own estranged mother, Grace, appeared at the event and suggested they meet up again, though Sariah is cautious about it. Evelyn confides that she also had a visitor who gave her false hope about the lace. The experience, however, has made her realize she may have been looking for her birth mother in the wrong place. She tells Sariah she now believes she needs to search in London. The two women share a hug, acknowledging their new friendship.

Evelyn’s attempts to find Frances Parfait online are unsuccessful, though she finds a profile indicating Frances retired from the British Museum in 2009. The search leads her to think of Asa; she looks for him as well but finds no trace. The memory of a mistaken sighting of him in Cornwall years earlier surfaces, reminding her of how carefully she has avoided her past in London. Concluding that her only option is to go in person, Evelyn decides to travel to Frances’s flat in Fitzrovia.

Evelyn travels to London by train. Walking through her old neighborhood, she imagines the alternate life she might have had if she had stayed with Asa, noting that she might have eventually become estranged from her parents. She finds Frances’s apartment building and rings the bell. A nurse named Samuel answers and is reluctant to let her in, explaining that Miss Parfait is very ill, but Frances—after he goes upstairs to convey Evelyn’s name—agrees to see her. Upstairs, Evelyn finds Frances frail and terminally ill. Upset, Evelyn asks Frances directly for the truth.

Frances explains she is not Evelyn’s mother but confirms she had a long, intermittent affair with Edwin. She admits Edwin may have had other girlfriends but believes he never would’ve had a baby with one, dismissing the idea that he is Evelyn’s birth father. She reveals that Edwin was a fraud who was fired for plagiarism at Oxford but never left. He stayed on in local accommodation, acting as if he were still a student and charming Evelyn’s mother. 

He later arranged Evelyn’s museum traineeship for his own gain. During his visits, he would send Evelyn on errands so he could steal uncatalogued artifacts. Frances’s own career was tarnished by suspicion following the thefts, and she admits she was relieved when Evelyn’s disastrous accident shifted the museum’s focus. 

After their conversation, as Evelyn leaves, Samuel confirms Frances has cancer and only weeks to live. On the train back to Cornwall, Evelyn processes the destructive truth about her father. She texts Sariah about her unsuccessful trip. Soon after, she receives a message from Frances, who has remembered two details Edwin once mentioned about Evelyn’s birth mother: She was young, and Frances feels sure her name was Agnes.

Back at the museum, Evelyn checks a backlog of messages from the committee confirming a member of the town council wants them to attend an interim meeting on Monday. Recalling advice Frances gave her, she makes a list of older citizens she could speak to find information about her mother, noting that her parents rarely had acquaintances or visitors to the home. She decides to speak first to a local woman named Mrs. Moran, who considers the topic of Evelyn’s birth unseemly but accidentally implies that Edwin would’ve known more than her mother. After, she speaks to local men who attended the exhibition, and they awkwardly end the conversation when she mentions the name Agnes.

She goes to the pub to find another man on her list but instead runs into George. Embarrassed, she recalls kissing him on New Year’s Eve years earlier. In the present, he buys her a drink and a snack. She confronts him about his argument with a journalist at the exhibition, but he explains that he was diverting attention away from the museum’s collection of forgeries and stolen objects. He corroborates Frances’s story about Edwin stealing artifacts in London, revealing that Edwin and George’s father had an arrangement to sell these pieces to secret buyers using the museum as a front. George tried to ward the journalist off because they might have noticed the forged painting or recognized the lingering pieces from London.

Evelyn admits she still owns boxes of collected items from Edwin that she never opened, believing they were worthless and would only renew her grief. She briefly wonders what he did with the money from his criminal activities. More pressingly, museum’s publicity now further endangers her, as it’s filled with boxes of easily recognized, stolen historical artifacts.

The perspective shifts to Alison preceding the museum exhibition. She has been confined to her home for nearly two weeks by her emotionally abusive husband, Roy. He controls her movements, has taken her phone, and isolates her from friends. On the night of the exhibition, Roy refuses to let her go, claiming she looks unwell, and takes their young son, Will, with him instead. He returns late, drunk and belligerent. He boasts about having hit Jacob and reveals that her father, Keith, became very upset about something at the exhibition and stormed out. The incident solidifies Alison’s resolve that she and her son cannot continue living this way.

While Roy sleeps that night, Alison retrieves her phone. She confirms her fear that her grandfather’s secret love affair, connected to the embroidered picture, was revealed at the exhibition, which explains her father’s distress. She has a crisis about whether to stay or leave Roy.

Sariah, Della, Evelyn, and Jacob gather in a conference room for the interim meeting with the town council. Jacob still has a black eye and seems disappointed that Alison won’t respond to their messages. Three men and a woman enter the room, including Mr. Palmer, who had been emailing them. The councilmembers appear skeptical about the prospects of Della’s and Evelyn’s businesses. Spurred by a desire to strengthen their proposal, Della surprises everyone with a promotional video and a speech about how she and Evelyn plan to combine the museum and ice cream shop into a single venue. The council agrees to take six weeks to consider the proposal.

Worried for Alison, the group decide to visit her house. Roy is away at work. They see the curtains move, implying Alison is home, but dismiss calling the police for a welfare check in case it causes Roy to react negatively toward her. They decide to wait, but Alison never comes outside.

Alison waits as Jacob and Sariah wait outside her house. Candi Staton’s “Young Hearts Run Free” plays on the radio, sparking a happy childhood memory and giving her courage to act. She runs out and waves them down. They help her pack and collect Will from nursery before driving to her father’s house. There, Alison finally feels safe and tells her father that it was neither her fault nor his that she stayed with Roy for so long. She accesses a document kept at her workplace that lists the history of domestic abuse she’s experienced, with dates and photos for each incident.

A few days later, Alison visits the museum and reads the text accompanying her grandfather Frederick Blake’s embroidery. It was submitted by Steven West of St Mawes, who reveals that he and Frederick were secret lovers. Evelyn appears and is horrified when Alison explains the connection, realizing she caused Keith Blake public humiliation. Alison forgives her, insisting it is better for secrets to be out in the open. She suggests returning the embroidery to Steven. The idea of returning things resonates with Evelyn, who thinks of the stolen artifacts her father hid in the museum. Alison departs, telling Evelyn the exhibition benefited everyone despite the painful revelations.