Sydney attends a tense Sunday dinner at her mother’s home, where Sasha still lives. Sydney feels a pang of jealousy observing her mother and sister’s easy intimacy. The dinner conversation becomes strained when Sasha teases Sydney about trying to get pregnant and Grace asks invasive questions about her fertility benefits and egg-freezing options.

After dinner, the sisters argue in the kitchen. Sydney confronts Sasha about her stagnant career and her decision to continue living at home at age 35. Sasha retaliates, accusing Sydney of being judgmental and emotionally distant. She points out that Sydney avoids any genuine conversation about her own life, effectively shutting her and their mother out. Sydney leaves the house feeling angry and estranged from her sister.

While sitting in her car after the fight with Sasha, Sydney reflects on her deceased father. She recalls his slow development of an addiction to alcohol and the pattern of emotional abuse that dominated her childhood. Her memory focuses on a particularly traumatic night when a drunken Larry, enraged that the family had taken a short trip without his full awareness, hurled a glass tumbler that shattered against the wall near her mother’s head. He then rose and approached them, threatening to “end [them] all” (85), words that her mother dismissed as “all talk.” 

Afterward, Grace strictly forbade Sydney or Sasha from ever speaking of the incident, enforcing their family’s rule that whatever occurs in their household cannot be spoken about outside the house. Connecting this memory to her current investigation, Sydney now wonders if her father’s extreme reaction to their temporary absence was driven by the unprocessed trauma of his sister Carol’s disappearance years earlier.

Unable to find Michael Hall online, Sydney calls his mother, Eloise, and gets his phone number. She leaves Michael a voicemail. Meanwhile, Barbara sends the digitized police records, a disorganized and overwhelming collection of files.

The intensity of the investigation triggers memories of Sydney’s past career as a crime reporter. She recalls covering the McEwan case, in which evidence—scuff marks indicating sudden acceleration rather than braking—suggested that the father deliberately drove the family van off a cliff, leaving no survivors. The case led her to have a mental-health crisis, resulting in a diagnosis of brief psychotic disorder. That night, unable to sleep, Sydney begins organizing the police files into a spreadsheet. The next morning, Malik finds her asleep in a chair. He’s deeply concerned when he discovers a notebook in her lap where she has obsessively written Carol’s name over and over in her sleep.

The night before Sydney’s egg-retrieval procedure, Malik cooks a romantic dinner. He confides in her about immense stress at his company, Wealthmate, and admits that he’s considering stepping down as CEO. Feeling overwhelmed by her own investigation, Sydney tells Malik that she feels unqualified. He suggests that she seek help from “citizen detectives” in online true-crime forums. 

The next day, Sydney undergoes the retrieval, and the clinic successfully extracts eight eggs. Afterward, while walking outside, she’s frightened when she looks at a mirrored building and, for a moment, sees Carol’s reflection instead of her own. 

In a diary entry, Carol writes about her and Michael’s plan to run away together, noting their disagreement over destination: Michael wants California, where he hopes to study law and intern at his uncle’s Oakland firm, while Carol wants Detroit to pursue her Motown dream.

The morning after her egg retrieval, Sydney wakes from a nightmare about being trapped by vegetation in deep water. As she studies a photo of Carol, she feels a strong connection to her aunt, seeing her as another young woman who was forced to mature too quickly to protect her younger brother.

While re-examining the police files, Sydney focuses on a key detail: A few people claimed to have seen Geraldine and Sally enter a dark, early-1950s sedan on the days of their disappearances, with one person speculating that it was a Chevy 210. Following Malik’s advice, she creates a detailed post about the six missing Raleigh girls, including photos and known facts, and shares it across several popular true-crime websites and forums. By making the case public, Sydney feels like she’s finally ensuring that her aunt Carol is no longer a family secret.

Michael Hall calls Sydney and confesses that he and Carol were deeply in love and secretly dated. He says that they had planned to run away together but fought about their destination shortly before she vanished. Michael claims that he filed a missing-person report for Carol and later moved to Detroit to look for her. He also reveals that he has a trunk of her belongings and invites Sydney to come see it.

After the call, Sydney finds a cryptic note in the police files stating that a “Y. Hall” canceled a report for “C.S.” 11 days after Carol went missing. Sydney is convinced that this means Michael’s sister, Yvonne, rescinded the report. She decides to go to Detroit, and Malik agrees, provided she doesn’t travel alone. Sydney resolves to ask Sasha to accompany her. These developments revive old fears tied to her previous diagnosis of brief psychotic disorder—fears triggered not by the Detroit decision itself but by recalling the McEwan case and reflecting on whether her father may have struggled with an undiagnosed mental illness that he could have passed on to her.

Sydney and Sasha fly to Detroit and go to Michael’s home, where they meet his wife, Rosa, and daughter, Maya. Michael explains that his sister Yvonne’s argument with Carol at the Shaw party stemmed from her disapproval of their relationship. Yvonne, home from law school for a visit, had intercepted his slipping grades at their mother’s house, blamed Carol, and came to confront her—ultimately forbidding Carol from seeing him. When Sydney shows him the police note about the canceled report, Michael dismisses it, suggesting that Carol herself could have called to cancel it using Yvonne’s name as a final act of defiance. He remains unpersuaded by Sydney’s theory.

He then shows them Carol’s old steamer trunk, which he offers to Sydney. While in his study, Sydney notices a framed photo from March 1965 showing Michael and his college friends posing with a dark Chevy 210. Michael identifies the car’s owner as his friend Raymond Green, a former student who lost his scholarship and was a likely candidate for the Vietnam draft; Michael assumes that he fled to Canada. Sydney immediately connects Raymond’s car to the witness statements. 

A final diary entry from Carol describes a terrible fight with her mother about her plan to run away and her brother Larry’s heartbroken sense of betrayal.