It follows Riyo, who arrives in Hawaii as a "picture bride" for a man she has never met before. The story is based on the historical practice of (mostly) Japanese and Korean men in the United States for work sending away to their homelands for wives.
The next day, she is given an ID tag to wear around her neck, with her employee number on it. She then goes into the fields for the first time, unfamiliar with farm work. The old woman who was the unofficial leader of the women prompts Kana (Tomita) to help the newcomer learn. Kana, herself a picture bride who had arrived several years before, is at first brusque and critical, but Riyo wins her over as a friend and they become close. Riyo begins to believe that the singing she hears at night is Kana.
Riyo begins saving her earnings in a tin can, with the intent of buying passage back to Japan, and Matsuji pointedly begins saving his own earnings in another can, saying that he intends to get another bride. An uneasy truce develops, until Kana tells Matsuji to become romantic, and to take Rudolf Valentino as a role model in the task of winning Riyo's heart. His campaign breaks down some walls, but the relationship remains platonic.
Working conditions on the plantation are difficult, with Antone, the Luna (field supervisor), driving the workers to do more work. The old woman who had been the leader leaves with her family for a new life in Honolulu, giving her employee's neck tag to Kana, with the admonition "Take care of the girls!"
As a mother, Kana is frequently concerned about the workers' children, who are left, unsupervised, under a sunshade in the field where the parents are working. She stands up against Antone to get the kids moved closer when the workers go to a new field, though moving the kids and shelter takes up working time.
Tragedy strikes. Preparatory to harvesting, cane fields are set on fire to burn off the leaves. Antone in a hurry to get the job done, doesn't know that Kana's daughter, Kei, has wandered into the fields. Kana rushes into the burning field to save her daughter, and both are lost.
A few nights later, Riyo leaves the house for some private time, and Matsuji follows the sound of her singing. He asks if she is meeting a lover, and they talk for a while, until she confesses her hidden shame. Her parents had died of tuberculosis, in a time when such a death put an onus on the family, though Riyo herself had been certified as healthy.
Matsuji rejects her, even when she reaches out to touch him as they lay in bed.
Betrayed, the next day she gathers her savings and a few belongings and runs away, eventually finding herself at the beach. That evening, as she dozes, Riyo is awakened by the sound of singing, and glimpses of a woman in the shoreline rocks. She follows, discovering that it is Kana's spirit, leaving for Japan. When Riyo asks the go with her, Kana criticizes her, not unkindly: "Who waiting for you there?" Then, as the old woman had done, Kana hands her neck tag to Riyo and tells her "Take care of the girls!" Kana turns to walk toward the sea and Japan, fading out of sight.
Riyo returns to the plantation and to her house, finding Matsuji drunk. She puts him to bed, and he looks at her, saying "I thought I was all alone again." Later that night, she wakes up and looks at him, then hesitantly reaches out to touch his hand, and he reaches back. The marriage is finally consummated.
The next day, Riyo is singing in the fields, as had Kana and the old woman, and Antone realizes that she has picked up the mantle of leadership. But she still hears Kana singing at night . . .
The film began with a voice-over (by Nobu McCarthy), and now ends the same way, as a mature Riyo explains "Now, when I hear singing in the fields at night, it's not Kana . . .it is the voice of my daughter, singing her daughter to sleep . . ." and she reminisces about coming home, to Hawaii.