Flashlight

Published in 2025, Flashlight is a literary novel by Korean-American author Susan Choi. The novel began as a short story under the same title, which Choi published in The New Yorker in 2020. As she expanded the story into novel length, Choi drew from her childhood experience of visiting Japan, as well as the historical disappearances of people from Japan in the 1970s. As of this writing, Flashlight is shortlisted for the 2025 Booker Prize.

The novel concerns the sudden disappearance of a man with Korean and Japanese ancestry named Serk Kang. Over several decades, Serk’s wife, Anne, and daughter, Louisa, reckon with the emotional consequences of this traumatic event, probing their memories for clues to the disturbing truth behind Serk’s disappearance. Choi explores Loneliness in Family Life, The Limits of Human Memory, and Tension Between Belonging and Identity.

This guide is based on the 2025 Farrar, Straus and Giroux Kindle edition.

Content Warning: The source material and this guide feature depictions of cursing, death, physical abuse, child abuse, sexual violence, graphic violence, racism, ableism, illness, mental illness, suicidal ideation, death by suicide, and emotional abuse.

Plot Summary

Serk Kang, an electrical engineering professor, suddenly disappears during an evening walk along the Japanese coastline. Serk’s daughter, Louisa, is the only witness to the event; however, she has sizable gaps in her memory. Serk is presumed dead. Louisa develops behavioral issues at school, partly to antagonize her white mother, Anne, who has multiple sclerosis.

The novel flashes back to 1945. Serk (originally spelled “Seok”) is born to a Korean family, but he only realizes that this is his heritage at the end of the World War II when Korea is divided to reflect the power shifts of the Cold War. When Serk’s family decides to move back to North Korea out of sympathy for the Communist Party, Serk and his sister Soonja elect to remain in Japan, where they are treated as second-class citizens by the Japanese government. Serk pursues an opportunity to study in the United States with the intention of seeking permanent residency.

At the same time, in the United States, 19-year-old Anne gives birth to a boy named Tobias. Because the pregnancy is unplanned, Anne gives Tobias up to be raised by his father, Adrian. Anne settles in Massachusetts, where she meets Serk through professional connections in academia. Serk and Anne quickly enter a passionate relationship, though Serk is reluctant to discuss his family, telling her instead that he has none. They get married and have Louisa, who proves to be a precocious child.

In the mid-1970s, Anne meets Tobias for the first time. When an accident sends Tobias to the hospital, he is discovered to have a brain tumor. Anne asks Louisa to keep Tobias a secret from Serk. Meanwhile, Serk is paranoid that the United States government will discover his parents’ affiliation with the Communist Party. He corresponds with Soonja, who reports that their parents may soon return to Japan for medical treatment. She urges him to come, and though Serk is reluctant, his college offers to sponsor his family in an academic exchange program.

In 1978, the Kang family arrives in Japan. Louisa tries to become more proficient in Japanese to hide her multiple heritage. Anne, who is experiencing the early symptoms of multiple sclerosis, seldom leaves the house. Serk, meanwhile, meets with Soonja to discuss their parents’ delayed travel to Japan. When Serk introduces Soonja to Louisa, he does not reveal their sibling relationship and instead calls her his friend.

Tobias also moves to Japan. He starts visiting Anne regularly, and Louisa is shocked to learn that Tobias is her half-brother. Soon, Serk announces his decision to rent a summer house by the sea. Anne’s disability alienates Serk, who spends more time with Louisa. Eventually, Serk disappears on a walk. Louisa is found barely alive on the shore, unable to recall what happened.

Anne and Louisa return to the United States. A decade later, Louisa moves to New York for college. Anne befriends her neighbor, a Korean War veteran named Walt. The two quietly acknowledge each other’s loneliness and marry. Walt discovers a radio broadcast that Anne recorded in Japan and recognizes it as a message delivery system used by North Korean intelligence agents. Anne wonders if it had anything to do with Serk’s paranoia.

During the summer of her junior year, Louisa travels to Europe. Despite her best efforts to avoid emulating her mother’s naivety, Louisa’s journeys are fraught with unexpected challenges and harrowing errors. In London, she meets Roman, whom she initially distrusts but eventually falls in love with. They marry and have a son named Julian.

It is revealed that Serk is still alive. He was abducted by the North Korean government and forced to teach their agents how to blend in with Japanese citizens. Serk only cooperates because he is convinced that Louisa was abducted as well. Once he antagonizes the North Koreans, however, he is sent to a reeducation camp for several years.

Following the death of Walt, Anne goes through her old letters and remembers the sudden disappearance of the only other Korean man in Serk’s department. Tobias, meanwhile, learns of a group that advocates for Japanese citizens abducted by North Korea. This brings him into contact with Soonja, who is still grieving Serk’s disappearance. Finally, Louisa connects a diary entry that Tobias gave her to a memory of the Kang family visiting Hawaii shortly before moving to Japan. Tobias visits to inform her that Serk is alive after all.

Serk escapes North Korea during a time of political upheaval. He spends time with two men called the Reverend and the Fisherman, who espouse opposing methods for liberating North Korean political prisoners. Believing that Louisa may still be incarcerated, Serk works with the Fisherman, Ji-hoon, to learn of her whereabouts. When Serk experiences cognitive decline, Ji-hoon establishes a contact with a former officer of the United States State Department named Roger, who promises to help Serk.

Reunited with Serk, Louisa visits him at the hospital several times, hoping that he might recognize her. At first, Serk mistakes her for a number of people, including his own father and his brother. When Serk finally calls Louisa by name, Louisa remembers the night of Serk’s disappearance. Serk is grateful that Anne insisted on Louisa’s swimming lessons, which guaranteed her survival. Louisa lies to him that Anne is still alive, which grants him relief before he dies.