In 1429 A.D., a young country girl known simply as Joan of Arc, or sometimes simply as The Maid, is given an interview by Robert de Baudricourt since she will not leave until she speaks with him. She tells him that she needs horses and armor to go to the Dauphin of France and to raise the siege of Orleans, a city held captive by the English forces. She knows that a siege would be possible because the voices of Saints Margaret and Catherine have told her what to do. Upon being convinced by The Maid's simplicity, Captain de Baudricourt grants her request.
Upon arriving at the Dauphin's castle, The Maid encounters all sorts of difficulties, especially with the Dauphin, who wants nothing to do with wars and fighting. When France's military fortunes and predicament are reviewed, Joan's demands that something be done to improve France's condition fall on deaf ears, but when she is alone with the Dauphin, she is able to instill enough courage in him so that he finally consents to let her lead the army, knowing full well that she can't make France's condition worse.
Joan then goes to the Loire River near Orleans, where she encounters Dunois, the commander of the French forces; he explains the necessity of waiting until the wind changes, but Joan is determined to lead her forces against the English stronghold without waiting; suddenly, the wind does change favorably, and Dunois pledges his allegiance to The Maid.
Sometime later, in the English camp, Warwick, the leader of the English forces, and his chaplain, de Stogumber, are maintaining that The Maid must be a witch because there is no other way of accounting for the heavy English losses and defeats except by sorcery.
The Bishop of Beauvais, Peter Cauchon, enters and discusses the fate of Joan of Arc. Cauchon's principal intellectual concern is that Joan is setting up her own private conscience in place of the authority of the Church. Warwick, who is not influenced by the concerns of the Church, is, instead, concerned that Joan is telling the common people and the serfs to pledge their allegiance directly to the king, whereas the entire feudal system is based upon the lower classes pledging their allegiance to their immediate lords and masters. Joan's simple pleas can possibly destroy the entire feudal system. Cauchon also adds that Joan is trying to get the common people to pledge further allegiance to their native countries (France and England) instead of to the Universal Catholic Church, an act which would further lessen the power of the Church. Thus, for different reasons, both agree that The Maid must be put to death.
After more victories, Joan has finally been able to fulfill her promise to drive the English back and have the Dauphin crowned king in the Cathedral at Rheims. After the ceremony, Joan is anxious to move on and capture Paris and drive the English from the city. The Dauphin, however, is content now with what he has recaptured, Commander Dunois is hesitant to start another campaign after all of the recent successes, and the Archbishop is beginning to find Joan to be too proud and defiant. Joan then realizes that she must stand alone in the same way that "saints have always stood alone," and in spite of the warning that if she falls into the enemy's hands, neither the military, nor the state, nor the Church will lift a hand to rescue her.
Some nine months later, Joan is standing trial for heresy. She has been imprisoned and in chains for these nine months and has been questioned many times about the validity of her "voices." After many complicated theological questions, her accusers force Joan to admit that her voices were not heavenly sent voices but, instead, came from Satan. After her recantation of the voices, her judges then sentence her to perpetual imprisonment and isolation, living off only bread and water. Joan rejects this horrid punishment and tears up her recantation. She is immediately carried to the stake and burnt as a witch; afterward, the Executioner enters and announces that Joan's heart would not burn.
Some twenty-five years later, in an Epilogue, Joan reappears before the king (the former Dauphin) and her chief accusers, who have now been condemned by a subsequent court, which has pronounced Joan innocent of all charges and her judges guilty of all sorts of crimes.
The time then moves to 1920, when Joan is declared to be a saint by the Church. As such, she now has the power to return as a living woman, and she asks everyone present if she should return. This is a horrifying prospect for them all, and they all confess that they wish her to remain dead. Joan then asks of God, "O Lord, how long before the world will be ready to accept its saints?"