Mai is a twelve-year-old girl from Laguna Beach, California. She excels academically and loves her coastal lifestyle. Forced to abandon her summer plans, she accompanies her grandmother to Vietnam. She secretly understands conversational Vietnamese but hides this skill from her family. She prefers comfortable American clothes and struggles initially with the heat and unfamiliar cultural expectations.

Bà is the aging matriarch of Mai's family who fled Saigon in 1975. She raised her seven children alone after her husband went missing in action. She possesses deep wisdom and maintains a close, mostly non-verbal bond with Mai. A new lead from an investigator prompts her to return to her ancestral home in search of answers.

Út is a Vietnamese village girl who stands out from her peers with her buzz cut, ragged trousers, and sun-tanned skin. She rejects traditional beauty standards and prefers the company of her pet frog. She communicates with Mai through written English notes before they find common ground.

Anh Minh is a Vietnamese student studying abroad in Texas who serves as Mai's primary translator and cultural guide. He speaks English with a pronounced Texas accent. He takes his education seriously and tries to teach Mai the tonal complexities of the Vietnamese language.

The detective is an elderly investigator hired by Mai's family. He claims to have located a former prison guard with information about Mai's missing grandfather. He speaks with an overly formal, poetic style that often requires translation.

Mai's father is a physician who travels to mountainous regions in Vietnam annually to conduct a surgical clinic. He insists that Mai accompany Bà to her home village. He worries about his mother's emotional well-being regarding the search for his missing father.

Ông is Mai's grandfather who disappeared during the Vietnam War after being taken as a prisoner. He worked alongside a guard digging tunnels. His memory hangs heavily over the family, driving their current trip.

The guard is an older man who was forced to dig tunnels during the Vietnam War. He is the last known person to have seen Mai's grandfather alive. He is reluctant to travel and share his story, creating a roadblock for the family's search.

Montana is Mai's best friend in Laguna Beach. She develops physically faster than her peers and attracts attention at the beach. Her loyalty to Mai comes into question when she begins spending time with Mai's crush.

Kevin is Mai's crush from school in California. Mai worries obsessively about him spending time with Montana during the summer break while she is thousands of miles away.

Mai's mother is a hardworking lawyer in California who stays behind during the trip. She communicates with Mai via phone calls and text messages, offering advice and trying to enforce daily vocabulary lessons.

Cô Tâm is Út's mother. She runs a local embroidery circle and tries to teach Mai traditional stitching techniques. She struggles to understand her daughter's rejection of traditional grooming.

Lan is Út's older sister. She catches the romantic attention of Anh Minh, creating a small love triangle dynamic with Con Ngọc. She lacks braces but is still considered beautiful by her family.

Con Ngọc is a local girl who actively flirts with Anh Minh. She wears trendy clothes and tries to emulate Western styles, once revealing a thong to get Anh Minh's attention.

Cô Hạnh is an aunt figure who takes an active interest in Mai's well-being. She provides botanical face masks for Mai's sunburn and administers strict traditional remedies when Mai gets sick from pond water.

Ông's brother provides lodging for Mai and Bà. He tends to wild doves in a birdhouse built by his missing sibling. He shares stories of losing his own son and wife, offering Mai a glimpse into the village's shared history of loss.

Froggy is Út's pet toad. He is overweight from Út constantly feeding him insects. He serves as a point of initial tension between Mai and Út when Mai accidentally makes him sick with a pebble.

Cô Nga is a busy dentist relative living in Hanoi. She provides lodging for Mai and Út but relies on her assistants to chaperone them due to her heavy workload at the government clinic.

Chị QH is an assistant to Cô Nga. She takes the girls shopping for clothes and helps them exchange currency, trying to manage their chaotic schedule in the bustling city.

Chị BêBê works for Cô Nga to earn a recommendation for dental hygienist school. She guides the girls through Hanoi on mopeds but panics when they disobey safety instructions.

Văn is a moped driver in Hanoi. He helps facilitate the girls' late-night excursion to catch glowing frogs and negotiates with local children on their behalf.

Lulu is one of the moped drivers who assists Văn in transporting Mai and Út around Hanoi, particularly during their sightseeing tours.