Sea of Tranquility by Emily St. John Mandel was written during the COVID-19 pandemic and published in 2022. It is a science fiction novel that explores time travel, the nature of reality, art, and love, as well as pandemics. The title is a reference to the cartographic feature of the moon, and the moon plays a key symbolic role throughout the novel. Sea of Tranquility is longlisted for the 2023 Andrew Carnegie Medals for Excellence in Fiction and is on Barack Obama’s 2022 annual summer reading list.

Plot Summary

Sea of Tranquility follows a time traveler, Gaspery-Jacques Roberts, and the people he encounters in the 1910s, 1990s-2020s, 2200s, and the 2400s. Gaspery’s identity is not revealed until the middle of the novel. The novel first follows Edwin St. John St. Andrew, Mirella Kessler, and Olive Llewellyn in their respective times, before arriving in 2401, Gaspery’s time. The novel returns to the earlier times after this point, eventually ending in 2195. At this moment, Gaspery has become violinist Alan Sami, whom the young Gaspery interviews. This intersection of the same person doubled in time creates the anomaly (an overlapping of moments in time) that the Time Institute sends him to investigate, inadvertently spreading the anomaly through all the times he visits.

The novel begins in 1912 and tracks Edwin as he travels around Canada; his parents have sent him there from England with a considerable allowance. He generally spends his time people-watching but also learns to draw. One day, he witnesses the anomaly, which momentarily transports him from the forest in Caiette to the Oklahoma City Airship Terminal where Alan plays his violin. After this, Edwin encounters Gaspery in disguise as a priest and tells him about the anomaly.

Part 2 focuses on Mirella, who is looking for Vincent Smith in 2020. The two women lost touch after Vincent’s husband cheated Mirella’s husband using a Ponzi scheme. Mirella attends a concert by Vincent’s brother, composer Paul James Smith, where he shows Vincent’s footage of the anomaly in Caiette as a teenager. Mirella learns that Vincent died mysteriously. After the concert, Mirella encounters Gaspery, who talks to Paul about the footage. Mirella recognizes Gaspery from her childhood in Ohio (his future, her past) and breaks up with her girlfriend after talking to him in New York.

Part 3 introduces Olive, a novelist on her book tour in 2203. She travels around Earth, missing her family who live on the moon colony where she was raised, and lectures about pandemics. A pandemic is breaking out as she tours, and one of her publicists, Aretta, is secretly a time traveler who will not tell her that she will die in the pandemic. Gaspery introduces himself as a journalist and interviews her, asking about a scene in her book that describes the anomaly.

Part 4 focuses on Gaspery’s journey to becoming a time traveler in 2401. He grows up near Olive’s house on the moon colony and meets a girl up the street named Talia. Many years later, Talia hires him as a security guard for a hotel in a different moon colony. While working there, Gaspery’s sister, Zoey, tells him about the anomaly, and he decides he wants to investigate it. He spends many years training at the Time Institute, including learning about the previously introduced characters. Then, he is sent to interview Alan the violinist first, but the Institute—and Gaspery at this point—do not know that Alan and Gaspery are the same person.

In Part 5, Gaspery interviews Olive and warns her that she will die on Earth in the pandemic if she does not immediately leave the book tour and go home to her husband, Dion, and daughter, Sylvie. Olive heeds his warning, goes back to Colony Two on the moon, and is safe in lockdown. She gains a new appreciation of life on the moon, jotting down her observations, giving virtual lectures, and writing a new book. Gaspery checks on Olive, and Zoey comes to the moon to warn him about the consequences for breaking the Time Institute’s rules about revealing the future to people in the past.

Part 6 shows Gaspery convincing Zoey to send him to Caiette in 1994, where he witnesses Vincent record the video of the anomaly that Paul plays at his concert. He sees how reality breaks at this point—with different people from different times crossing paths in the forest and the airship terminal. When Gaspery returns to the Time Institute, he convinces Zoey to send him to two more locations. The first is a party that Vincent and Mirella attend in New York in 2007. Gaspery asks Vincent about the video, and she confirms that she experienced the anomaly.

Part 7 opens with Gaspery visiting Edwin in 1918. Edwin is back in England with his parents after being severely wounded in the war, both physically and mentally. Gaspery assures Edwin that, while his mourning of his brothers and lost lover in the war is appropriate, the anomaly was not a symptom of a mental illness, but an occurrence that has been verified by several people. This knowledge keeps Edwin from ending up in a psychiatric care facility; he dies from the 1918 flu at home with his family.

When Gaspery returns once again to the Time Institute, Zoey is being arrested. Gaspery is sent to the Ohio of Mirella’s childhood, where he is framed for murder, arrested, and imprisoned. He lives in prison until his sixties, when Zoey helps him escape to Oklahoma City in 2172. She also helps Talia escape to the same place and time. Gaspery and Talia are reunited, get married, and play the violin together.

In Part 8, after Talia dies, Gaspery becomes Alan and plays violin in the Oklahoma City Airship Terminal. This act is what triggers the anomaly—several Gasperys appear at the same time and place. He goes through the interview with his younger self without revealing his true identity and is content with his life, even if the anomaly proves that he is living in a simulation.