Helen is haunted by visions of Lorna’s dead body. Stan offers to bring her to his yacht, but Helen wants to witness her family’s reaction when the police arrive. At the villa, she finds Naomi passed out beside scattered pills, which Helen hides. She joins Freddy, and Ciro in the garden and notices a deep cut on Ciro’s hand. They show her a newspaper article revealing that the investigation into Sarah’s death is being reopened. Helen realizes Richard and Marcus must have used their influence to prevent the story from being printed on the front page. When Freddy tries to comfort her, she smells Lorna’s perfume on him and pulls away. She rushes to her room to find that Sarah’s necklace and Lorna’s pregnancy test are both missing. Ciro follows her, and Helen tells him that Lorna is dead, only to realize from his lack of surprise that he and the rest of the family already knew.

Sarah tells Marcus that she is getting a divorce from Richard. She promises a quiet separation, and Marcus concedes that Richard’s jealousy over her career is a core problem. Sarah reflects on the affair she had with Marcus years prior, which ended when Sarah became pregnant with her daughter, Helen. Richard believes Helen was born prematurely. Sarah and Richard’s marriage worsened after moving to Los Angeles, where Richard isolated her and suppressed her career. During that time, a supportive gesture from Marcus led to a kiss, which began their affair. 

Over drinks, Sarah tells Marcus about her new play, Saltwater, which depicts a wealthy family ruined by internal conflict, though she denies that it is about the Lingates. Specifically, the family loses all their money and tries to act as though they are still wealthy. As they walk back to the villa, Marcus asks her to remain amicable for one last family dinner. Sarah agrees, promising him that Richard will never learn that Marcus is Helen’s biological father.

Ciro tells Helen that Lorna’s body was found that morning. As he leaves, the Italian police arrive. Marcus provides them with the blackmail letter, claiming they gave Lorna cash for a payoff and believed she had run off with it. This story gives the family an alibi and a motive for a third party to have killed Lorna. The lead officer is skeptical and reveals the reopening of the investigation into Sarah’s death, suggesting the two events are connected. Richard is stunned by this news, but Marcus calmly denies any involvement in either death. When Naomi appears, Marcus tells her Lorna drowned, though the police had not yet mentioned how Lorna died. Naomi collapses, and Richard reads the newspaper clipping over and over.

After the police post a guard outside the villa, Helen learns her father has disappeared. Ciro calls and tells her that Richard is at the ruins of Villa Jovis, sitting dangerously close to the edge of a cliff known as Salto di Tiberio. Taking the manuscript of her mother’s play, Saltwater, Helen rushes to meet him. She finds her father distraught over the reopened investigation. He confesses that he is haunted by visions of Sarah and that he is to blame for what happened. Overcome with guilt, he confesses that he killed Sarah. When she asks if he also killed Lorna, Richard insists he is only talking about Sarah. Helen flees, but as she runs through the ruins, she is grabbed and pulled into the shadows.

Sarah drinks heavily at the party at Casa Malaparte. Two producers approach Sarah and offer to fund her next play, which makes her feel like she has a chance to leave Richard. When Richard confronts her, he pleads for them to work on their marriage, but Sarah knows it is over. She slips away, wandering to the Salto di Tiberio, but Richard follows her. She tells him she wants a divorce. Richard insists they cannot divorce because the public filings would expose the family’s secrets. Sarah realizes he is protecting himself and the family from the same financial problems she made up in her play. He grabs her snake necklace, cutting his hand, then releases her, pushing her off the cliff.

Ciro grabs Helen, and she tells him about her father’s confession. Ciro takes her to Renata’s cottage. Ciro leaves to work, and Helen asks Renata about the night of Sarah’s death. Renata describes the Lingates as “corrosive,” saying they lie and are never caught. The next morning, Helen wakes in Ciro’s bed. Helen understands her father confessed because he knows she is financially dependent on him and will be forced into complicity. She returns to the villa, where Freddy tells her they are all expected at a party that night on Gallo Lungo, an even more isolated island.

A 2018 article from The Sun announces that the billionaire Werner Leipling has purchased the Li Galli islands, a small archipelago between Capri and the mainland. The main island, Il Gallo Lungo, is habitable but inaccessible except by private boat or helicopter. It has long been a secluded destination for the elite. The article closes with a quote from writer Graham Greene, who said of the island: “The place looks idyllic, but might be hell” (214).

Freddy tells Helen he has made them an appointment at a jeweler, implying an impending proposal. Helen feels trapped but agrees to go. Before they leave, she finds Sarah’s necklace has been returned to her room. At the jewelry store, Helen asks the jeweler, Tomasso, to appraise the necklace. He performs a quick test and reveals it is not gold but a “pinchbeck,” a well-made but old replica from the 19th century. Helen is disappointed to learn that the necklace is a fake, since she always hoped that one of the calls, letters, or artifacts people claimed came from her mother were real.

Helen and Freddy return to the villa to find police questioning Marcus and Richard. The police present a grainy security photo of Lorna walking with an unidentified man on the night she died. Helen sees Naomi react with a flicker of recognition, but Naomi says nothing. The police then reveal that Lorna was four to five weeks pregnant and that they intend to use fetal DNA to identify the father, requesting samples from the men. Marcus refuses on their lawyer’s advice. Alone with Helen, Freddy confesses he slept with Lorna and fears the baby is his. In return, Helen admits she has been having an affair with Ciro for years. Furious, Freddy storms away. Naomi, having seen the fight, approaches Helen and offers to take her out and tell her a story.

Naomi pretends to be asleep on the couch as Richard and Marcus enter the villa. She listens as Richard confesses he followed Sarah, who demanded a divorce. In a panic, he pushed her on the steep slope of the garden and left her. Marcus takes control, creating a cover story: They will claim Sarah went for a walk and was robbed and murdered. He then leaves to retrieve Sarah’s jewelry and throw it into the sea to sever any connection to the body. As they head upstairs, Richard insists it was an accident.

Naomi takes Helen on a shopping spree, but they only look at items for Naomi. She tells Helen that she cannot have children, so she plans to make Helen her sole heir. Helen assumes this is an apology for the family’s decades of lies, and she is relieved to know that she might become independent from her father when Naomi dies. When Helen reveals that Freddy was sleeping with Lorna, intending to assuage Naomi’s fear that Lorna’s child belonged to Marcus, Naomi dismisses her and shows Helen a bank statement from her and Marcus’s joint account with a $500,000 payment to Lorna, which Naomi believes was for an pregnancy termination. Naomi reveals that she already forgave Marcus for one affair that led to a pregnancy, but she cannot for getting a second woman pregnant. She implies that Marcus is Helen’s biological father and that he was repeating his past infidelity with Lorna. Before Helen can process this, Naomi claims that Richard did not kill Sarah.

Marcus leaves the villa to retrieve Sarah’s jewelry from her body and dispose of it in the sea to stage a robbery. He finds Sarah alive but injured and disoriented. He feigns concern and leads her back toward the villa along a deserted route. When a group of tourists appears, Sarah cries for help, but Marcus convinces them she is his injured sister-in-law. As they near the house, Sarah understands that Marcus intends to kill her. She pleads with him, promising to keep the secret that he is Helen’s father. At the villa gate, Naomi is waiting. Sarah screams for help, and Naomi steps forward, clamps a hand over her mouth, and tells her to be quiet.