Plot

A famous author goes on a cruise trip with her friends and nephew in an effort to find fun and happiness while she comes to terms with her troubled past.

Alice is convinced to attend an award ceremony in GB. She does not fly hence she is offered to cruise from NY to Southampton, along side two old college friends and her nephew. The journey is a set for the four to talk and re-establish relationships and past differences. There's a fifth person in disguise. Yet the finale reshuffles a set trajectory

Alice Hughes (Meryl Streep) is a Pulitzer Prize-winning author working on her latest manuscript, which her publisher hopes will be a sequel to her best-known work, You Always/You Never. Alice is receiving a literary award in the United Kingdom but is unable to fly due to her health, leading her agent Karen (Gemma Chan) to suggest she make the transatlantic crossing on the Queen Mary 2. Alice invites her nephew Tyler (Lucas Hedges) to assist her while on the voyage, and her university friends Roberta (Candice Bergen) and Susan (Dianne Wiest), with whom she has lost touch. Susan lives with her son Eddie, and Roberta works as a salesgirl in a department store.

Alice and Roberta have a difficult relationship stemming from Roberta's belief that Alice used details about her in You Always/You Never, which Roberta feels derailed her life. Robert confesses to Susan that she feels bitter about the entire experience as she got nothing out of the whole deal. Unbeknownst to Alice, Karen joins them on the ship, hoping to learn details about Alice's new book. She and the publisher have no idea what Alice has been writing and they need a sense of the same to steer Alice in a different direction, if she is going too off track. They all want Alice to write a sequel to her previous book "You Always/You Never".

Once on the ship, Karen strikes up a friendship with Tyler, using him to gain information from Alice. Alice tells Tyler that the book is about "trying to catch lightning in a bottle for a second time", possibly implying that it will be a sequel to a previous work. She spends the majority of her time writing, only taking breaks to eat and swim.

Roberta attempts to attract wealthy men on board (she wants Tyler to Reece them and figure out if they have any criminal histories), while Susan begins interacting with Kelvin Krantz (Daniel Algrant), another writer; Krantz writes popular mystery and thriller books, which Alice dismisses (although Alice reads his novels in secrecy). Krantz also knows Karen and advises her not to pry into the details of Alice's work.

Roberta continues to avoid meeting Alice in private, while Karen continues to strike a friendship with Tyler to try and get some details on Alice's book. Tyler gets drawn to Karen and spends more and more time with her. They go to the planetarium and to the disco together.

Tyler tells Karen that he saw a black man coming out of Alice's room, just before he went in for breakfast. They speculate that Alice might be having a secret affair. Karen tells Tyler about her boyfriend Jan, with whom she went out for years. And then he dumped her just 2 months ago, and now she is worried about plans for the rest of her life. She wanted to have kids with Jan.

Roberta attempts to meet with Alice to seek an apology and acknowledgment of Alice's use of her life details - a fact that Alice has never admitted to - but the two fail to connect. Roberta made an appointment to meet Alice at the tearoom at 2 PM. but when Alice showed up, Roberta was on a date with a wealthy gentleman, and this offends Alice as Roberta wasted her time and interrupted her work.

Roberta tells Susan that she is convinced that Alice brought her on the trip to learn what happened to her after her divorce, so she can use that in her book. Alice runs into Tyler and Karen together and learns that Tyler has a romantic interest in Karen. Tyler and Karen have dinner, where Tyler's romantic advances are rejected.

Alice invites Karen to dinner with the foursome, where tensions come to a head between Alice and Roberta after Karen asks about the new book. They are interrupted by Susan, who accuses them both of being selfish and holding onto their bitterness. Alice decides to delete her book, implied to be a sequel to You Always/You Never as both Karen and Roberta expected.

After disembarking the ship, Alice and Roberta have a conversation about their estrangement. Roberta tells Alice that she will provide her with the life details Alice would need to write a sequel to You Always/You Never but wants a 30% share of the profits in return. Alice rejects this offer (she offers to cut her a check instead for money) and they part with Roberta telling Alice "I loved you when you were Al." That evening, Alice begins work on a new writing project. The next morning, a man that Tyler saw frequently coming out of Alice's room on the ship greets him at Alice's door. He reveals that he is Dr. Mitchell (John Douglas Thompson), Alice's personal physician, and that Alice has died in the night from deep vein thrombosis; Dr. Mitchell was aboard the ship to administer injections of a blood thinning medication to Alice.

Tyler, Roberta, and Susan visit the grave of 19th century author Blodwyn Pugh, as Alice had intended them to. Back in the United States, Roberta gives Alice's writing, which she took from Alice's room after her death, to Karen in the hopes of profiting from it. Karen maintains that the work is unfinished and cannot be published but encourages Roberta's idea of writing a book about her life experiences. Susan works with Krantz on a new book based on an idea of hers she shared with him aboard the ship. Tyler receives Alice's unfinished writing from Karen and returns it to her apartment, recalling a talk Alice made celebrating the existence of consciousness and the ability of people to affect each other.