The following version of the book was used to create this study guide: Lai, Thanhha. Listen, Slowly. Harper Collins, New York, NY. 2015. Kindle AZW file.

Mai has turned 12 years old, meaning she is now old enough to ride the bus from her family home in Laguna, California, to the beach. But, just as summer is starting, Mai is forced to travel to her parents' native country, Vietnam. Traveling with her is her father Mua and her grandmother Ba. Mua returns here every summer to perform surgeries on children with cleft palates and terrible burns. This year, Ba has come in the hope of finding closure regarding her husband. Mai's grandfather, Ong, was listed as missing in action decades earlier during a terrible war in Vietnam. Though no one has heard from him, Ba has apparently never fully dealt with the loss. Mai hopes that Ba will see that Ong is not here and be immediately ready to return to America. Instead, they meet with a detective who has tracked down a guard who was the last person to see Ong alive.

While Mua goes to begin his work, Mai and Ba travel to the village where Ba and Ong began their life as a young married couple. They are greeted by many people anxious to reveal their connections to Ba and Ong. Mai has little information about Vietnam other than what she absorbed from documentaries, and she is surprised to discover there is a lot of focus on food. Ba and Mai settle into Ong's ancestral home, still occupied by Ong's younger brother. Mai meets an interesting girl named Ut who always carries a frog, but she feels she has little in common with Ut or anyone else. She continues to hope that she and Ba will soon return to America.

As the weeks pass, Ut and Mai begin to bond over a series of shared experiences. They find that they can communicate. Mai can understand most of the Vietnamese she hears, Ut writes in perfect English, and Ut can understand English if Mai speaks slowly. The detective brings the guard to see Ba. The guard, a man named Thuong, tells Ba about Ong's life during his final months. Though Ong's body was never found, there is little hope that he survived a night when he simply tired of the horrible conditions of forced labor in a small tunnel. Ba angrily walks away, but Mai hears Thuong say that Ong left a message. Mai sets out for Hanoi to find Thuong and push the process of getting closure for Ba.

More time passes and more money exchanges hands before Thuong leads a small group back into that tunnel. There, Mai, Ba, and Mua trace the letters of seven names that Ong had carved into a wall. The letters were the names of Ong's children. The words were from a sentimental line Ong included in every letter he wrote to Ba. Once they return to the city, Mai realizes she could insist on returning to California now that Ba has received Ong's final message. Instead, she asks what Ba wants. They return to Ba's home village where they lay a lump of clay from the tunnel along with a special tile in the family's burial plot. Though they have not recovered a body, Mai realizes that this is enough. With 12 days left until the date of their return flight, Mai again knows she and Ba could go home early. Instead, she settles in to learn more Vietnamese from Ut while she teaches Ut proper English pronunciation. This gives Ba time to say her final farewells to friends and the place where Ong grew up.