This scene is set in a great hall arranged for a trial, with a circular table surrounding a rough wooden stool for the prisoner. Approximately nine months have elapsed since Joan's capture, and, as we learn later, Warwick has ransomed Joan from her captors and has turned her over to the ecclesiastical court to be tried for heresy. Warwick, who is forbidden to be present at an ecclesiastical trial, has come to inquire of "Pious Peter" Cauchon about the progress of the trial. The court has already held six public and nine private examinations, and there seems to be no progress. Cauchon introduces Warwick to the Inquisitor (Brother John Lemaitre), a seemingly mild, elderly man, and to the chief prosecutor, Canon John D'Estivet. The Inquisitor informs Warwick that all evidence is in, and they are ready to proceed. Warwick is informed that all that is desired by Joan's judges is to save her soul, but he demands Joan's death as a political necessity; ironically, The Maid herself is her own worst enemy: Every time she speaks, she convicts herself with blasphemies.
As Warwick departs, the court assembles. De Stogumber and Canon de Courcelles protest to the court that their sixty-four meticulously drawn-up charges have been reduced to only twelve indictments. The Inquisitor, backed by Cauchon, explains that the court is not interested in "trumpery issues." The "great main issue" is heresy, and all of the wild, silly accusations about magic serve only to confuse the issues.
At this point, a young priest, Ladvenu, wonders if Joan's heresy is due only to her simplicity. The Inquisitor answers in the longest speech in the drama, asserting that heresy often begins with simple people who are often generous, lovable, humble, and charitable, people who are "saintly simpletons"; heresy, he says, begins when a simple woman rejects her clothes for the dress of a man and continues until this "vain and ignorant person" sets up her own judgment against that of the Church and attempts to interpret God's will, believing always "honestly and sincerely that [her] diabolical inspiration is divine." Furthermore, The Maid is pious and chaste, but "diabolical pride and natural humility are side by side in her." He admonishes her judges that they must avoid being either too cruel or too sympathetic toward her: "Remember only that justice comes first." Cauchon agrees with the Inquisitor, and he reminds the court of the great danger called "Protestantism," in which private individuals set up their own private judgments against the collected wisdom of the Church, thus threatening the "mighty structure of Catholic Christendom."
Joan is brought in, chained by the ankles and showing the strain of the long imprisonment and harsh treatment. She is immediately attacked on some minor points by prosecutor D'Estivet. When Joan balks at swearing to tell the truth once more (for the tenth time), she is threatened with physical torture. After more time is wasted on trifles, Bishop Cauchon then asks Joan the essential question: "Will you submit your case to the inspired interpretation of the Church Militant?" Joan agrees to obey the Church only if it does not ask her to deny the heavenly origin of her voices; furthermore, if the Church bids her to do something contrary to God's command, she cannot consent. This assertion causes extreme consternation among her accusers, who consider it heresy to even think that the Church could suggest something contrary to God.
When Ladvenu pleads with Joan to accept the authority of the Church, Joan maintains that she has never disobeyed the Church, only that God must be served first, and she believes herself to be in a state of grace with God. Courcelles wonders if this was so when she stole the Bishop's horse, a silly question which causes disorder in the court. D'Estivet then charges Joan with having "intercourse with evil spirits" and of dressing like a soldier. Joan defends her voices as heavenly voices, and she explains impatiently the necessity of her dress in plain common sense terms: It would be foolish to live among soldiers while dressed as a woman, and, furthermore, in an enemy prison, it would be even more foolhardy to wear petticoats. As Joan continues to make impatient and pert or sarcastic replies, she is reminded that the Executioner is standing directly behind her, a man who confirms that the stake is ready for Joan's immediate burning. Joan finds herself in desperate despair: She is terrified of burning at the stake, but she asserts that her voices promised her that she should not be burnt. Ladvenu and Cauchon use her fears to make her confess that her voices have betrayed her: She finally agrees that her voices have deceived her because "only a fool will walk into a fire"; God would not expect her to go to the stake. Her judges are triumphant and immediately bring her "a solemn recantation of heresy" to sign. De Stogumber interrupts the proceedings and denounces the court, asserting that eight hundred Englishmen wait outside, ready to burn The Maid. When de Stogumber is quieted, Ladvenu reads to Joan the recantation which renounces her voices as false and states that she embraces the Church for bringing her to salvation, and, in addition, that she pledges total allegiance to the authority of the Church. Ladvenu guides her hand to sign the document, and Joan is pronounced free from the danger of excommunication, but because she has sinned most presumptuously, she is sentenced to spend the rest of her life in solitary confinement and perpetual imprisonment, living on only bread and water.
Upon hearing her sentence, Joan immediately denounces the recantation document, dreading imprisonment in a rat-infested hole more than the flames of the stake. She tears her confession to shreds and denounces the assembled court as fools. She cries out that she is not frightened of bread and water, but only of being shut away in darkness, of being denied the light of the sky, the sights of the fields; living in chains forever, she says, is impossible. To keep her from the very forces of life is the counsel of the Devil, for she, she states, is keeping God's counsel. She pronounces the court to be unfit for her to live among them. The Inquisitor and Cauchon immediately pronounce her "a relapsed heretic," and they state that she must be cast out and abandoned. Joan is brutally hurried to the stake, followed by Ladvenu, who will be by her side for her last confession. When the flames can be seen inside, Cauchon says that he wants to stop the burning because of some technical irregularities, but the Inquisitor stops him, explaining that the Church proceeded in perfect order, and it is the English who are guilty of irregularities. This fact might be useful in the future because of the innocence of The Maid. The Inquisitor then explains that Joan was innocent because she understood nothing about the proceedings; she was merely crushed by the Church and the Law.
As the Inquisitor and Cauchon leave to witness the burning, Warwick enters and is soon followed by de Stogumber, who staggers like a demented person to the prisoner's stool and sobs uncontrollably. When asked what the matter is, he blubbers out that he did not know what he was doing and did not know how horrible death by burning was. He is thankful that The Maid asked for a cross because an English soldier was able to give her two sticks tied together for her final consolation. De Stogumber says that he feels that he is damned, and he is admonished to control himself just as Ladvenu enters, carrying a cross which he held for The Maid to see during her last moments of life; he says that he climbed onto the burning pyre, but that Joan sent him back, admonishing him of the danger to himself. Ladvenu cannot understand how Joan could, at such a time, think of the safety of others unless she were with God.
When de Stogumber rushes out to pray among Joan's ashes, Warwick sends Ladvenu to look after the Chaplain. Then, unexpectedly, the Executioner comes to report that the execution is complete. Warwick wants assurance that no relics remain that could be sold; the Executioner, however, reports that Joan's heart would not burn, but that all the rest of her remains are at the bottom of a river. When verbally assured that he has heard the last of The Maid, Warwick, with a wry smile, wonders if he has truly heard the last of Joan of Arc.
The very setting of this scene is intensely dramatic. Joan is placed on a rough wooden stool surrounded by her adversaries — with no one to defend her except herself and her innocence; her denial of a defense counsel is a contradiction of modern law, and of particular note here is the fact that all representatives of the Church maintain that she needs no defense because they all want to save her soul; this statement and all like it must be viewed as cruelly ironical and hypocritical because after Joan is convicted, the Inquisitor acknowledges that she was completely innocent. Likewise, the title "saint" in the play's title, as well as Joan's subsequent rehabilitation, puts the audiences completely on Joan's side against the prosecutor. Of course, the Inquisitor knows from the beginning that Joan is innocent. This is Shaw's point. As with Warwick, who knows that Joan has not deliberately plotted to destroy the feudal system, but that her innocent statements are damning and that The Maid must die for political reasons, the Inquisitor also knows that Joan's innocence is more dangerous than any calculated plot against the Church itself. But, if the Church allowed people to follow their own simple consciences and their innocent instincts, feelings that "seemingly" come directly from God, then the entire structure of the Church would be undermined. Joan, in her innocence, has no desire to destroy the Church, but in following the purity of her own voices (that is, her own conscience), she becomes the greatest possible threat to the authority of the Church — for if everyone followed the dictates of their own conscience, then the entire structure of the Church would collapse. Consequently, the beginning of Joan's entire damnation occurs when the Church's representatives ask her if she will forgo her own opinions (her voices) and accept the judgments of the Church as completely authoritative.
The Inquisitor, in his long speech, points out that great heresies occur when simple, innocent people like Joan begin to trust in their own consciences rather than listen to the authority of the Church. The Church can exist only when it has total authority, and it must stamp out any dissent or "Protestantism." The existence of the Church is more important than the life of a simple country maid. If Joan is allowed to live, then other, also innocent country people might begin to trust their own personal judgments and ignore the Church's interpretations and authority. Consequently, Joan must die for the sake of preserving the status quo of the feudal system of the authority of the Church. Anyone, however innocent, must die if that person tries to set up "the private judgment of the single erring mortal against the considered wisdom and experience of the Church." Consequently, as the Inquisitor points out, Joan in her innocence constantly condemns herself, especially in such statements as the following: "In case the Church should bid me to do anything contrary to the command I have from God, I will not consent to it, no matter what it may be." This statement is enough to hang her since she has openly asserted that the Church might indeed suggest something contrary to God, and the further implication is that Joan, a simple maid, can interpret God's message better than can the Church. This is indeed "Protestantism."
Dramatically, Shaw plays off his simple spokesman for truth against his crafty, ambiguous characterizations of the representatives of the Church. For example, the Inquisitor is presented as a kindly old gentleman who professes a deep concern over the personal welfare of The Maid. But behind the Inquisitor's facade is an iron mind which knows that Joan is innocent, that she is not in league with the Devil, and that her failure to intellectually understand the charges will condemn her in spite of her innocence. But like Warwick, the Inquisitor knows that Joan must be sacrificed for the sake of the authority of the Church. Thus, behind the kindly facade is the determined mind of the Executioner. Likewise, the greatest dramatic change occurs in the character of de Stogumber. In earlier scenes, as well as here, de Stogumber is presented as a comic figure. His ferocity in demanding that The Maid be convicted and burnt as a witch is therefore dramatically contrasted to the change in his character after witnessing the actual burning of The Maid; now, his early ferocity and hatred turn inward upon him, and we see him ultimately as a repentant, sobbing hysterical man.
Throughout Joan's testimony, in addition to her common sense, her gentle faith, her innocence, her simplicity, and her transcendent beauty shine through the depressing Inquisition as though it were her saintly halo. Indeed, throughout the entire scene, Joan is seen as a person of great common sense, a person whose answers are so incontrovertible that it makes her questioners seem like fools. Yet even though Joan is right when she tells D'Estivet, "Nobody could be such a fool as to believe" what he has just told her, yet her very answer suggests that she has not the proper respect for the authority of the Church even though the questions of the Church are stupid and foolish. Her explanation about the nature of her dress (one should not dress in feminine finery when one is being guarded by the enemy in a dungeon) depends on basic common sense; yet she is convicted partly on the fact that she refuses to wear fine dresses in her situation. Joan's greatness and the turning point in this scene occur in her defiant act of tearing up her recantation. Here, Joan represents Shaw's dynamic "Life Force" — a force that cannot exist in the confinement of a dungeon hole. For Joan to live without the sky, the church bells, the fields, and, in essence, without freedom is more frightening than burning at the stake. Joan's last act of freedom is to choose death rather than to submit to perpetual imprisonment. And in so choosing death, Joan has set the path for her canonization and her sainthood.