Captain Arthur Keller, a retired Civil War officer who edits a town newspaper in Tuscumbia, Alabama. He is a haughty man in his mid-fifties, apparently accustomed during his military career to instant and unquestioning obedience to his every whim. Disappointment at the seeming cowardice of his teenage son and the terrible physical affliction of his small daughter gnaw at his heart, causing him to be irascible and sharply demanding at times with his family. Underneath, he is a concerned and loving father and husband. He is especially frustrated in his efforts to dominate Annie Sullivan, Helen’s teacher, finding her persistence and inner courage more than a match for his chauvinism.
Kate Keller, the young second wife of Captain Keller and mother of Helen. For more than five years, she has tried unsuccessfully to cope with Helen’s random destructive movements and angry tantrums. With a new baby in the family, she realizes the desperate need to teach Helen self-control. With gentle persuasion and a sure instinct for her husband’s temperament, Kate manages to persuade her husband to hire Annie as a teacher and to let her have her way with Helen.
Helen Keller, a child of seven who lost both sight and hearing as a result of high fever during a babyhood illness. Locked inside the dark cage of her body, she is unable to communicate her simplest wants and needs to others except through violent tantrums and howls resembling those of a hurt animal. She has become a tyrant in her home and a menace to her infant sister. As a last effort to control her, Captain Keller hires a young governess, Annie Sullivan, to teach her simple human conduct. Helen’s yearning for knowledge leads her far beyond behavior control to the discovery of language and all that this discovery opens to her in terms of life and love.
James Keller, Helen’s teenage half brother. Living in awe of his domineering father, James has grown resentful of his stepmother, Kate, and of Helen, who demands so much attention and care that he feels cheated out of the family love he desires. With the arrival of Annie, he is able to see a model of brave resistance to circumstances and to his father’s demanding ways. Through her influence, he begins to grow toward asserting his own personhood.
Aunt Ev, Captain Keller’s sister. As a kindly and concerned aunt, Ev spoils Helen with small treats and supports Kate in her efforts to get help for the child.
Viney, the Keller family servant. Amid the turmoil of a household that revolves around the whims and temper of a handicapped child, Viney manages to keep a stable and good-humored manner. Her children, Martha and Percy, are playmates for Helen.
Mr. Anagnos, the headmaster of the Perkins Institute for the Blind, the school where Annie was trained. It is Mr. Anagnos who chooses Annie for the difficult assignment of teaching Helen.