Rachel is a spirited native Hawaiian girl who contracts Hansen's disease at a young age. Authorities exile her to the Kalaupapa settlement on Moloka'i, separating her from her family and childhood home. She maintains her connection to the ocean through swimming and surfing. As she matures in the settlement, she learns to balance the strict medical regulations with her desire to build meaningful connections.

Henry is a merchant sailor who travels the world and brings back exotic dolls for his youngest daughter, Rachel. He struggles with his marriage to Dorothy and holds a deep appreciation for his Hawaiian heritage. He grieves the political changes in his native land and the subsequent separation from his daughter.

Dorothy is a devout Christian mother in Honolulu who insists her children use Christian names. She attempts to heal and conceal her daughter's early symptoms of Hansen's disease to avoid social shame. The pressure of her daughter's diagnosis profoundly affects her community standing and faith.

Henry's charismatic brother faces exile to Moloka'i shortly before his niece is sent there. He attempts to serve as a caretaker for Rachel in the settlement despite his own rapidly advancing illness. He provides a familiar, comforting presence in an otherwise frightening environment.

Haleola is a native Hawaiian healer on Moloka'i who originally came to the island to care for her first husband. She preserves traditional Hawaiian legends and spiritual practices, passing them down to younger residents. She serves as an essential maternal figure for Rachel.

Sister Catherine is a young Franciscan nun originally from New York who travels to Hawai'i to care for the residents of the Bishop Home. She provides medical care and emotional support to the young girls on Moloka'i while harboring a deep personal grief over her father. She forms a tight, sometimes contentious bond with Rachel.

Crossen is an American sailor exiled to Kalaupapa who harbors intense bitterness about his diagnosis. He regularly turns to alcohol, physically abuses his girlfriend, and creates significant danger and tension in the settlement.

Kenji is an educated former stockbroker from Honolulu and the son of Japanese immigrants. Exiled to Moloka'i after developing Hansen's disease, he manages the local store. He finds renewed purpose and affection through his growing relationship with Rachel.

Ruth is Rachel's daughter, born on the island of Moloka'i under strict separation rules that prevent physical contact with her parents. Named after a beloved nun, she faces an uncertain future as authorities mandate her adoption away from the settlement.

Sarah is Rachel's older sister. As children, she and Rachel frequently quarrel over toys and attention. Their relationship faces severe tests as illness and social stigma disrupt their family structure.

Ben is one of Rachel's older brothers. He grows up in the bustling environment of Honolulu before his family faces the disruption of the health inspector's visits.

Kimo is one of Rachel's older brothers. Although his mother prefers his Christian name, James, the rest of the family uses his Hawaiian name. He grows up in Honolulu before family circumstances force significant changes.

Francine is a young girl who meets Rachel during their initial quarantine. They travel to Moloka'i together and reside at the Bishop Home. As she grows older, she takes up horseback racing in the settlement.

Emily is a resident of the Bishop Home who becomes one of Rachel's roommates and closest friends. She offers comfort to younger girls experiencing homesickness and openly appreciates the safety the settlement provides from her previous life.

Leilani is a new arrival at the Bishop Home who identifies as a māhū, a third-gender person in Polynesian culture. She teaches Rachel how to braid hair and encourages her to participate in island social events.

Mother Marianne is the authoritative nun who oversees the Bishop Home for girls in Kalawao. She enforces strict rules regarding separation and morality but occasionally turns a blind eye to minor infractions committed by the residents.

Dr. Goodhue is a dedicated medical professional at Moloka'i. He administers experimental treatments to the patients and tracks their health progress, specifically monitoring skin tests for signs of disease remission.

Moko is an isolated older man living in the hills of Moloka'i. When Rachel becomes lost in the rain, he forces her to do manual labor in exchange for his initial help.

Jake is a young assistant lighthouse keeper on Kalaupapa. He shares a brief romantic connection with Rachel over literature before his fear of her illness causes him to pull away.

Grandpa Maka is Henry's father, who leads a traditional ho'oponopono healing ceremony for the family. He emphasizes the importance of Rachel's true Hawaiian name, Aouli, in restoring her health.

Sister Victor is a moody Franciscan nun who works alongside Sister Catherine. She fears the patients and struggles significantly with life in the settlement, eventually suffering a breakdown.

Felicia is a resident of Moloka'i who dates the sailor Gabriel Tyler Crossen. She frequently suffers from his volatile temper and physical abuse.

Wyckoff is a health inspector who visits schools and homes in Honolulu to identify individuals showing signs of Hansen's disease. He ultimately escorts Rachel to the receiving station.

Margaret is Pono's wife, who faces the sudden upheaval of her marriage when authorities search for her husband. She separates from him following his diagnosis.

Keo is Haleola's first husband, who contracted Hansen's disease and passed away in Kalawao. His illness is the reason Haleola originally traveled to the settlement.

Will is Dorothy's brother who brings fish to the family's Steamer Day celebrations in Honolulu.