The Wars of the Roses (1455-1485) being over, Richard of Gloucester determines to gain the throne occupied by his brother, Edward IV. He first manages to turn Edward against the Duke of Clarence, who is imprisoned in the Tower on the charge of treason. Next, he wins the hand of Lady Anne, even as she follows the hearse bearing the body of the murdered Henry VI. As part of his plan, Richard succeeds in convincing Hastings and Buckingham that the queen and her faction are to blame for Clarence's imprisonment. Hired murderers carry out his instructions to put Clarence to death.
Richard joins the other members of the hostile factions in solemnly vowing in the presence of the dying Edward to hold the peace. The remorseful king learns that Clarence has been put to death before he himself dies. When the young Prince Edward is sent for from Ludlow to be crowned, Richard moves quickly to meet this turn of events. Buckingham, now Richard's "second self," promises to separate the prince from the queen's kindred. Lord Rivers, Lord Grey, and Sir Thomas Vaughan are imprisoned by Richard and are executed. The frightened queen seeks sanctuary for her son.
With a great display of courtesy and devotion, Richard has Prince Edward and his brother lodged in the Tower. Finding that Hastings remains loyal to the prince, the villain-hero denounces him as a traitor and orders his execution. Soon thereafter, Rivers, Grey, and Vaughan meet like fates. Next, Richard convinces the Lord Mayor of London that he has acted only for the security of the realm. He has Buckingham slander the dead Edward, implying that the late king's children are illegitimate and that Edward himself was basely born. When citizens of London, headed by the lord mayor, offer him the crown, Richard accepts it with pretended reluctance. Arrangements are made for his coronation.
The despairing queen-mother fails in an attempt to visit her sons in the Tower just before Richard is crowned. To secure his position, the new king suggests to Buckingham that the young princes be put to death. But the duke falters at the thought of such a monstrous deed. Dorset, it is learned, has fled to Britanny to join Henry, Earl of Richmond. This turn of events does not deter King Richard. He has rumors spread that his wife is mortally ill; he arranges a lowly match for Margaret, Clarence's daughter; he imprisons Clarence's son; he engages Sir James Tyrrel to undertake the murder of the little princes. Buckingham, now treated disdainfully and denied the promised earldom of Hereford, resolves to join Richmond. Anne dies, and Richard offers himself as husband for his niece, Elizabeth of York. Richmond lands at Milford at the head of a mighty army. Joined by many nobles, he marches inland to claim the throne. Buckingham is captured and slain.
The two armies meet at Bosworth Field, and the two leaders are encamped on either side. That night, the ghosts of Richard's victims appear, indicting him and prophesying his defeat. In contrast, Richmond has "fairboding dreams" and is assured that "God and good angels" stand ready to assist him. Both Richard and Richmond address their troops before the battle begins. Richard fights courageously but is overcome and slain in personal combat with Richmond, who accepts the crown and proposes to marry Elizabeth of York, thus ending the dissension between the two great factions.