Henry V's funeral is attended by many of his noblemen, who speak sadly of the death of such a great king. Several messengers arrive, announcing trouble in France. Several towns, part of the English territory once won by Henry V, have been lost, the Dauphin Charles has been crowned king, while the English hero Talbot has been taken prisoner. Hearing the news, the noblemen rise to action, each taking on a different task to help reorganize the kingdom and prepare the newly crowned king--the former king's son, Henry VI--for his emergency duties in France.
Talbot's forces lay siege to Orléans, while Charles and his lords try to fight their way out. Yet the English, although exhausted and starving, still beat them. The Bastard of Orléans brings Joan to meet Charles. She says she has seen visions and can lead the troops. Charles challenges her to single combat and she beats him. She assures the French that she will break the siege that very day.
In London, the Protector of the kingdom, Gloucester, who will rule until the young king is old enough to take over, comes to blows with the leader of the church, Winchester, at the Tower of London. Winchester bars Gloucester from entering the Tower and accuses him of plotting to take over the kingdom. Their serving men join in the fight, but soon the Mayor arrives to split them up.
In France, Talbot has been released in exchange for a captured French lord. The French launch an attack on the English forces, killing important leaders. Talbot and Joan fight, and she gains the upper hand, but she says it is not his time to die, and she leaves him. Joan succeeds in lifting the siege, and the French nobles celebrate her successes. Yet Talbot engineers a sneak attack on Orléans and retakes the city, so that he can bury his dead comrades within the city.
The Countess of Auvergne sends for Talbot. She says she wants to see this renowned man in person. Talbot goes to her castle, where she now declares he has fallen into her trap. But Talbot laughs, saying he is not as small as he looks. Rather, he is just one part of a great army that will never be trapped. His soldiers arrive instantly.
Back in London many lords gather in the Temple Garden outside Parliament to dispute a point of law. Richard Plantagenet and Somerset form the heads of opposing camps, and they pluck white and red roses as symbols of their differing opinions. Their followers do the same. Somerset insults Plantagenet's father and they each scorn each other. Warwick predicts that the argument, though begun over something so small, will end in the deaths of thousands.
Plantagenet goes to the Tower of London to talk to his uncle Mortimer and to ask about his father. Mortimer says Plantagenet's father was once in line to the throne and had raised an army to help him claim his right to power, but he was captured and executed, while the rest of the Mortimer line, including this Mortimer, was suppressed. Mortimer dies, leaving Plantagenet even more anxious to regain his birthright.
All of Parliament soon learns of Gloucester and Winchester's dispute when their serving men crash into the room pelting each other with stones. King Henry urges them not to fight, for civil dissention will weaken the nation. The two men promise to stop fighting for the moment. Warwick presents Plantagenet's request to have his father's title passed on to him. The king grants it, also giving him his uncle's former title, and, thus, renaming him the Duke of York. Gloucester urges the king to go to France to deal with the unrest there, and Henry agrees. Exeter comments on the growing factionalism resulting from the noblemen's quarrels--that of Gloucester and Winchester and that of Plantagenet (now York) and Somerset--and refe rs to a prophecy stating that Henry VI would lose all the territories that his father had won for Britain.
Talbot's forces stand outside Rouen, prepared to attack. The French and English forces insult each other repeatedly. Talbot asks the French to meet him in the field and fight a fair fight rather than using their walled city to their advantage, but they refuse. The English forces manage to beat the French forces anyway. Joan tells Charles not to worry about the loss, because she has a new plan to weaken Talbot. Burgundy, a French leader fighting with Talbot, constitutes the only threat to her plan, but she lures him to the French camp and convinces him that he's fighting for the wrong side.
Henry arrives in Paris with his nobles. Talbot goes to meet him, where he receives a message from Burgundy about his change of loyalty. Talbot goes with his forces to try to talk to him. Meanwhile two underlings of York and Somerset ask the king for the right to have an armed fight. This is the first the King learns of the struggle between the followers of the white rose and the red rose. The king urges Somerset and York to put aside their differences while they are in France, for their dissention will make Britain appear weak to its enemy. The king says it shouldn't matter what rose he wears, since he loves both his lords--yet even as he says this he picks Somerset's red rose. York is upset but he keeps it to himself. Henry assigns the two men to new tasks in France, making York the leader of the English troops and putting Somerset in charge of the cavalry.
Talbot prepares to attack Bordeaux, but the city is well defended and Charles' forces approach from behind: he is trapped! A messenger from Talbot asks York to send the cavalry reinforcements to save Talbot, but York has no troops to send. Convinced Somerset has delayed the delivery of the cavalry out of dislike for him, York bemoans the imminent death of Talbot and the loss of the lands hard won by Henry V. The same messenger goes to Somerset, who says York is to blame for sending Talbot into battle without sufficient troops and that York probably did so knowingly, wanting to take over Talbot's post. The messenger says Somerset should have helped Talbot, and his death will be both noblemen's shame.
Talbot's son John arrives on the battlefield, having come to learn about soldiering from his father. But Talbot tells him he has arrived at a terrible moment and urges him to flee rather than die in his first battle. But John refuses, saying he will disgrace the honor of the Talbot name if he flees. The battle begins, and John is wounded; yet still he will not flee. Finally, John is killed and Talbot dies of grief. The English army is defeated.
Back in London, Gloucester reads letters from the pope urging the English to make peace with the French. Charles agrees to make an offer. Meanwhile in France, Charles' forces are under attack by the united front of Somerset and York. Joan calls to her patron-demons to advise her about the future, but they refuse to speak to her. York captures Joan in battle.
In the course of the battles, Suffolk has captured Margaret, a French girl, daughter to one of Charles' nobles, René. Impressed with her beauty, he wants to woo her, but he is already married. So he decides to woo her for Henry and asks René if he will consent to her marriage to the English king.
York and Warwick hold Joan in trial. They ask if it is true that her father was a shepherd, but she refuses to acknowledge this. She tries to convince them that they should not kill her, for she is a virgin and, thus, able in her purity to communicate with powers on high; they will incur a heavenly wrath if they execute her. York and Warwick nonetheless prepare to have her burnt at the stake. She now suddenly claims that she is pregnant and they wouldn't dare kill a pregnant woman, but York tells her that no matter what she says, she will die. She curses the English and is led away.
Meanwhile, Winchester tries to engineer peace between Charles and the English. At first, Charles resists, but his nobles advise him to accept the peace for the moment in order to stop the massacre of his citizens; they can always break the treaty later.
Suffolk arrives in London and tells the king of Margaret's charms. Henry decides that he will marry her, but Gloucester reminds him he is already engaged to the daughter of a relative of Charles, a match that would soothe international politics. Margaret's father Rene is only a minor earl with no money and, thus, a union with her would offer no real advantages. Yet Henry insists on marrying her and tells Gloucester he must simply forgive his choice. Suffolk has succeeded; now Margaret will rule the king and he will rule Margaret.