The following version of the book was used to create this guide: Oyeyemi, Helen. Peaces. Hamish Hamilton, 2021.

The novel opens with the first-person narrator describing his curiously unemotional breakup with a man named Honza Svoboda, using an informal storytelling style. As the novel continues, dialogue reveals that the narrator is Otto Shin. Otto boards the Clock Carriage on a sleeper train, The Lucky Day, with his husband, Xavier Shin, and pet mongoose, Árpád XXX. The inside of the train is characterized by disorienting and absurd visuals, such as furniture on the ceiling and a lack of lighting. Xavier sees a woman holding a sign that reads either HELLO or HELP, and believes the woman to be Ava Kapoor, the owner and resident of the train.

Through his internal narrative voice, Otto recounts the development of his relationship and engagement with Xavier. Xavier calls his aunt, Do Yeon-ssi, who is partying with a young man named Yuri, whom Xavier seems to remember. Otto explores the train and meets a woman named Laura in the sauna car while looking for the source of a mysterious song, which he suspects is played by Ava. Laura warns Otto against talking to Ava, but he goes to find her anyway. He stumbles across Ava playing the theremin. He also meets her pet mongoose, Chela. Ava tells Xavier that before living on the train, she played theremin for a man named Karel Stojaspal and his son who was not in the room with him, Přemsyl. She also mentions her girlfriend, Allegra Yu. She asks Otto about a fire. Otto tells her that he saw a man in a burning flat and tried to rescue him, but then realized that he’d imagined the man and had run into an empty flat. They connect over their shared experience of interacting with people who do not exist.

Otto returns to Xavier in the Clock Carriage. Xavier tells Otto about a train ride from his childhood, when he was living with two adults in Paris. During that train ride, two people, a young woman named Laura De Souza and her father, Eddy De Souza, join Xavier in his train car. All three of them are taken hostage by a woman who wants to play Baduk with the man in Xavier’s carriage. The encounter is resolved when the woman begins swallowing the game stones and Laura attacks her. The narrative returns to the diegesis, where Otto is listening to the tale. Otto and Xavier agree that they are disoriented and want to leave the train at the next stop.

The next day, Otto chooses not to awaken Xavier in time to leave the train at the next stop, where a maintenance team boards the train. Chela comes into Xavier and Otto’s carriage, pursued by a man carrying a dip-net, whose facial features Otto struggles to process. The man jumps out of the moving train and Otto and Xavier pull the emergency cord to stop the train, but no one is able to find his body. Allegra, who is dressed elaborately, arrives at the carriage to follow up with Otto and Xavier and chides them for causing trouble.

Otto and Xavier go to the kitchen carriage for breakfast, but the carriage is covered in food, so instead they shower off the sticky mess together. Xavier and Otto talk about Yuri, who is Xavier’s ex-partner. Xavier and Otto then go to the postal carriage, where they find correspondence to and from Ava Kapoor and the train itself. Through one of Ava’s replies to a hate message, they learn the history of Ava’s ancestors from the 1730s, who amassed a fortune through a tea-smuggling scandal.

Allegra interrupts Otto and Xavier by calling them to meet her in the picture gallery carriage. There, they look at four paintings, two of which are portraits (the first of a young man, and the second of the same man with his father), and two of which appear to be blank canvases, all painted by Přemsyl. Allegra tells Otto and Xavier that Karel left his estate to Ava on the condition that, when Ava turns 30, she take a psychiatric test to assess her sanity. Allegra suggested to Ava that they live in The Lucky Day to avoid stressful communications with strangers, in order to preserve her sanity. Laura joins the three in the picture gallery carriage and reveals that she is there for work as a “neutral observer” on behalf of insurance companies who have lent money to Ava on the expectation that she pay it back upon receipt of the inheritance (127). Both of them suspect that Přemsyl may sabotage the will, as Ava's 30th birthday is coming soon.

Xavier asks Otto why Allegra and Laura suspect that Přemsyl and Karel are related to the two of them. Otto avoids the question by suggesting that they go to eat breakfast. Ava is there in the kitchen carriage and makes them breakfast. She shares that she suspects that Allegra and Laura will run off together after the inheritance situation is resolved. She tells them that she has left a file in the bread bin for them to add to.

The file in the bread bin contains summaries of what Ava, Allegra, Laura, and Karel’s friend and executor Zeinab remember about Přemsyl. They describe an unsettling boy whom everyone but Ava was able to see and interact with. Otto adds his own letter, stating that the man in the burning flat was Přemsyl. Xavier also writes a letter stating that he has never met Přemsyl, but that Přemsyl reminds him of two of his ex-partners, Raúl and Tolay. Xavier and Otto agree that Přemsyl seemed to disturb Allegra and Zeinab, and that he wanted Ava's attention.

Merchants board the train for a bazaar to celebrate Ava’s 30th birthday, but she refuses to shop. Otto goes shopping, but is interrupted when Xavier suddenly clears the train and takes Otto to the back of the train with him. There, Xavier and Otto join Allegra and Laura, where they are confronted by Yuri in a full diving suit. Yuri ties them to the wall and berates Xavier and Otto for not staying with Honza and Tolay. Yuri is also ‘unseen’ like Přemsyl. Ava walks past them to the sleeper car and plays For Přemsyl At Night, the song Otto first heard her play on the train, and Yuri disappears. Ava returns to the car where the four other passengers await. Ava sees Allegra after Allegra kisses her, but ‘unsees’ Otto, Xavier, and Laura. Ava and Allegra leave with both Chela and Árpád.

The novel concludes with Xavier, Otto, and Laura disembarking to meet Do Yeon-ssi at the train station. Laura is informally adopted into Xavier’s family. Otto and Xavier are locked out of their Instagram accounts, but Otto delights in leaving footprints in the mud when it rains.