Soon after Dr. Robert Richardson arrives in the farming and fishing community on the small island of Cape Breton near Nova Scotia, Aggie McDonald begs him to assist in the birth of a calf. Aggie lives with her brother Black, a poor, proud farmer, and his deaf and mute daughter, Belinda. Although the McDonalds and the villagers consider Belinda mentally retarded, Robert teaches her sign language and lip reading. When Black learns that he can communicate with his daughter, a bond grows between them. One evening, a group of young people, including belligerent Locky McCormick and his girl friend, Stella Maguire, Robert's assistant, come by the farm to pick up some flour. An impromptu dance breaks out, and Robert places Belinda's hand on the violin so that she can feel the vibrations. Her tentative attempts to dance briefly attract Locky's attention. Later, having been rejected by Stella, who secretly loves Robert, a drunken Locky rapes Belinda. Belinda becomes withdrawn afterward, and Black begs Robert to find out what is wrong with her. Robert convinces Black to allow him to take Belinda to town for diversion. While there, Robert brings Belinda to an ear specialist for an examination and learns that she is pregnant. Back at Cape Breton, he reveals her secret to Aggie, but does not tell Black, fearing his anger. Black has become very proud of his transformed daughter and, accompanied by Robert, brings her to church for the first time. Locky and Stella attend the service as well, to hear their wedding banns read, and Belinda's reaction to Locky gives Robert cause to think that he may be the father of the child. He says nothing, however, and after the baby, whom Belinda names Johnny, is born, the townspeople, believing that Robert is the child's father, ostracize him and the McDonalds. Robert offers to marry Belinda, but Black dissuades him, stating that Belinda will understand that he does not love her. When Locky appears during a storm, Black suddenly realizes the identity of Johnny's father, and assaults Locky, who pushes Black off a cliff to his death. When a lack of patients forces Robert to leave town, he promises to send for Aggie and Belinda as soon as he is established. Meanwhile, certain that Belinda is incapable of caring for her child, the townspeople decide to take the baby from her and give him to Stella and Locky, who have since married. Stella changes her mind, however, when she sees how much Belinda loves Johnny. Locky then tells Stella that he is determined to take the child because he is the baby's father. When he comes after the baby, Belinda shoots and kills him. At Belinda's murder trial, Stella initially refuses to disclose the reason why Locky was killed, but finally tells the truth, and Belinda is acquitted.