Lainey’s feelings for Tyson are new and surprising to her. Worried about how he will react, she distracts herself by starting to read the script for her movie. Tyson brings her a muffin and reads her script along with her. They discuss what happened the night before, and Tyson points out that he would never be able to just climb, naked and uninvited, into a shower with a woman. Lainey recognizes “the inherent double standard that [she] live[s] by” (269). Lainey asks whether he thinks things would have worked out with Summer and tries to imagine her and Tyson being together. She invites Tyson to go out shopping, and he teases her about her outfit.

Tyson reflects that he might finally be seeing the real Lainey, without her customary defenses. He enjoys their time shopping and telling her about the history behind the places they visit. They go to a shop where Lainey designs a pair of sandals for herself and then buys a pair for Tyson. In one boutique, she asks Tyson to step into the dressing room to zip her up.

Hannah and Olivia walk along the Phoenician Steps and visit the chapel of San Michele. Olivia suggests hiking the Path of the Forts. At a narrow spot along the cliffs, Hannah freezes, and Olivia takes her hand. Hannah’s reaction makes her wonder if she has a crush on Olivia, though she’s never been attracted to a woman before. 

They pause to watch the sunset, and Lainey texts. She thinks that Hannah is with Archie. Hannah tells Lainey to go to dinner without her. She and Olivia visit a beach bar, and Oliva says that she admires Hannah, telling her, “You’re a badass” (285). Hesitantly, Olivia asks if Hannah has ever wanted to kiss a girl. Hannah replies that she hasn’t before now. When Olivia kisses her, Hannah kisses her back.

Lainey and Tyson discuss their feelings and wonder what Summer would think. Tyson reveals that he was struck by Lainey’s vulnerable look. Tyson advises her to become more self-aware, and Lainey realizes, “I have a premonition that I will one day think back to this moment. That it is a turning point” (287). Tyson shares that he wants the freedom to be himself and promises that when he figures out what he wants, Lainey will be the first to know. Lainey spots Archie and Ian and realizes that Hannah isn’t with them. Tyson admits that Olivia is on the island, and Lainey demands that they find Hannah.

Tyson realizes that Lainey’s three drinks are affecting her, and she refuses to calm down. They follow Hannah’s Life360 location to a hotel where Hannah and Olivia are seated at the bar. Lainey angrily confronts Hannah and is rude to Olivia. Then, she leaves. Hannah, remorseful, agrees to go back to the hotel with Tyson. Tyson sees her kissing Olivia goodbye.

Hannah tries to apologize to Olivia and then kisses her goodbye. Tyson admits that not telling Lainey the truth looks like a breach of trust. They discover that Lainey is not in the hotel room and has turned her Life360 off. They begin calling restaurants and clubs to try to locate her.

Lainey feels devastated that Hannah lied to her and that Tyson knew about it. Looking for Archie and Ian, she approaches the Croatian girls they were with. The girls invite Lainey to a party on a yacht. She puts her sandals in a basket and goes aboard the yacht, where she meets Jonathan, the yacht’s owner. She begins drinking and dancing, knowing that “the crash is coming. The crash always comes” (304).

Alessandro joins the search for Lainey and finds the taxi driver who took her to the marina. They locate the yacht, and Tyson recognizes Lainey’s shoes. He goes aboard and is confronted by the yacht owner, who becomes belligerent, threatening to call the police. Alessandro talks to the man and realizes where Lainey is.

Alessandro reports that Lainey became intoxicated and fell down one of the ladders on the boat. He drives them to the hospital, where the doctor informs them that Lainey has alcohol poisoning. Hannah updates Olivia, who plans to stay on the island until she knows Lainey is okay. They visit Lainey, and Hannah is shaken at her state. She and Tyson assure Lainey that they love her.

Being in the hospital reminds Lainey of the end of her mother’s life. The doctor informs Lainey that she experienced alcohol poisoning and recently had sex, which Lainey says was consensual. Her arm is broken and will be in a cast for several weeks, which will likely mean the end of her movie role. 

Hannah and Tyson bring her coffee, and Lainey feels ashamed. She admits that she drinks too much, and Tyson suggests that it might help to sort out her issues around her parents. Hannah explains that she is developing a relationship with Olivia. Lainey says that she trusts them, and Tyson replies, “Good. Because we will always have your back […] Even if we make some mistakes along the way” (325). Hannah points out that they kept their pact, and Tyson says that everything is going to be okay.

Tyson, Lainey, and Hannah are visiting Paris. They have all pledged to participate in the Chicago Marathon as part of a tribute team that Summer’s brother is organizing in her memory. Lainey has attended a rehab facility in Antigua and is nine months sober. Hannah, miserable in Atlanta with her mother and knowing that Grady and Berlin were together, moved to Texas and started her own boutique design firm. She and Olivia are dating, and Olivia has mentioned having children together. Tyson, who is dating Lainey, is moving to New York and will teach high school English.

Hannah reflects that she’s learned not to live small. She and Lainey meet Tyson and Olivia near the Eiffel Tower. Tyson hands Lainey a written copy of the Summer Pact with a new addendum: a proposal of marriage. He offers a ring, and Lainey accepts. Olivia joins in the celebratory pictures, and Hannah reflects, “[W]e are a foursome once again. As much as we will always miss Summer, I know that she is with us—and that we wouldn’t be here without her” (331). She is glad to know that their friendship has stood the test of time and that they are all working their way toward happiness.