The Duke of York enters the throne room with his sons and followers, wondering where King Henry has fled to after their recent battles. Warwick urges York to take the throne. As York sits, Henry enters with his followers, who want to fight York right there. Henry urges calm and asks York to descend from the throne. York makes public his alleged claim to the throne, while Henry defends his hereditary possession of the crown. Suspecting that his claim to the throne may be spurious, Henry asks York to let him rule while he lives, and he will pass the throne on to the house of York on his death. York agrees and departs, but Henry's nobles are astonished that he would deny his son the birthright of becoming king on his father's death. Margaret, Henry's queen, arrives and accuses him of being an unnatural father for having disinherited his son and a bad ruler for thinking that York will let him rule.
Back in the town of York, Richard's sons Edward and Richard, and his follower Montague, urge York to take the throne immediately, rather than await Henry's death. York insists he has sworn an oath to let Henry rule, but Richard easily convinces him that the oath was not binding. Meanwhile, Margaret's forces arrive to challenge York.
Richard's other son Rutland is captured and killed on the way home by Clifford, who wants to avenge his father's death at York's hand. York's troops are losing the battle, and York is captured by Margaret and Clifford. She offers him a handkerchief dipped in Rutland's blood and challenges him to wipe his tears with it. He rails against her, calling her unnatural, and Clifford and Margaret stab him to death.
Edward and Richard wonder about the fate of their father, when they see a vision of three suns on the horizon, which Edward believes is a sign that the three York brothers must become as one. Richard isn't so sure, preferring to keep his allegiance only to himself. A messenger arrives with news of York's death, and the brothers are devastated. Warwick and Montague prepare to march to spar again with Margaret's forces, this time bringing the aid of York's other son George's troops.
Margaret and Clifford, with their followers, meet Henry at the town of York. Clifford urges Henry to undo his disinheritance of his son, but Henry isn't convinced that sons automatically appreciate that which their fathers leave them, since he didn't enjoy his father Henry V's legacy. Edward and his men burst in and demand the throne. The nobles from each side insult each other, and Henry tries to speak, but none will listen to him. Edward blames Margaret's pride for the civil war, and he declares that they will have to argue on the field of battle, since she won't let Henry speak.
Richard hunts Clifford on the field of battle in order to revenge his brother's and father's death. The tides of the battle ebb and flow as Henry watches from afar. He sees two soldiers drag dead bodies away from the scene of the fighting, trying to find valuables to steal. As the soldiers remove the armor from the bodies, one discovers he has accidentally killed his own father, and the other, his son. Henry mourns that the battles of the nation have come to this level of unnaturalness. Henry's son Prince Edward urges him to flee.
Clifford is wounded and dies. Edward sees he has won the battle, though Henry is nowhere to be found. They head to London to crown Edward and to give new titles to Richard and George. Meanwhile, as Henry wanders through the forest, he is arrested by two men who support Edward. Edward sends Warwick to France to ask for the hand of the king of France's sister, and Margaret goes to France to ask for aid against Edward.
In London, Lady Gray petitions Edward to get her land back. He takes a liking to her and asks her to marry him. His brothers are annoyed to hear Edward's enthused announcement of his imminent marriage. Richard, alone, considers his potential route to the throne. Many people stand in his way, but what alternative is there? He could enjoy the pleasures of the court, but his physical abnormalities, including a hump back and withered arm, make him undesirable. Therefore, nothing remains for him but to connive and plot to get the crown. He decides he will play the role of the good brother and subject, while he plots ways to eliminate everyone in his way to the throne.
In France, Warwick and Margaret arrive at the same time. King Louis decides to give the hand of his sister, Lady Bona, to Edward, thus, denying Margaret aid, when a messenger arrives with news of Edward's marriage. Insulted to have been sent on a futile errand, Warwick changes sides, pledging his allegiance to Henry. Louis gives Margaret troops to fight with Edward.
In England, Edward and his brothers and lords discuss his marriage. They receive news that Warwick and Margaret have joined forces. George is so upset by Edward's new marriage that he leaves with Somerset to join with Warwick. In preparations for the coming battles, Edward is captured. Seeing George on the enemy's side, Edward gives up the throne and consents to be imprisoned at Warwick's brother's estate. Yet Richard and Hastings soon spring Edward from his gilded prison.
Warwick, George, and their nobles find Henry in the Tower and free him. Henry says he wants to be king in name only, and he names Warwick and George as joint protectors of the kingdom. They receive word that Edward has escaped to Brittany, from where he soon returns with reinforcements. Returning to the town of York, Edward thinks he wants only to be the Duke of York, but his followers urge him to seek the crown.
Henry's followers go to gather troops to battle Edward. Edward and Richard capture Henry and send him to the Tower before they march to meet Warwick's army. Edward's army meets Warwick's forces, and Edward asks Warwick if he will again swear allegiance to him. Warwick refuses. Warwick's supporters arrive, including George. Richard convinces George to break with Warwick, and the forces prepare to fight.
Warwick is wounded in battle and dies. Warwick's surviving supporters, Somerset and Oxford, go to join Margaret's army. Margaret urges on her forces, and they meet Edward's army. Edward wins this battle; he sends Somerset and Oxford away, kills Prince Edward, and imprisons a mourning Margaret. Richard sneaks off to the Tower, where Henry awaits.
Henry prophesizes that thousands will suffer because of Richard's deeds, for Richard was born under all the most inauspicious and evil signs. Richard kills Henry and declares himself separated from the ties of family and brotherhood. Since he was punished by the heavens with such unfortunate physical attributes, he will fight for himself alone hereafter. And with Henry and his son out of the way, Richard's next goal is to eliminate George and Edward.
Edward's son has been born, and George and Richard kiss the child. Edward calls for festivities to celebrate his attainment of the throne. At last there is no one to oppose him--except his own brother.