In 1483 England, Richard, the Duke of Gloucester (Vincent Price), is dismayed when his dying brother King Edward IV names their brother George, Duke of Clarence as Protector to his young son and heir, Prince Edward. Richard wants the position himself, to become de facto ruler after his brother's death. He secretly stabs George to death with a dagger bearing the crest of the Woodville family, framing the dying king's in-laws. Richard is now named Protector. His wife Anne approves of his crime and encourages him to take the throne for himself. After the death of King Edward, Richard tries to achieve his ends by intimidating the widowed queen's lady-in-waiting Mistress Shore into claiming that the dead king's two children are illegitimate. She refuses, and Richard tortures her. After she dies on the rack, Richard claims he executed her for spreading the rumour that the princes were illegitimate. He says that the two princes should be placed in his protective custody. The ghosts of Clarence, King Edward and Mistress Shore haunt Richard, warning him that they will be revenged at "Bosworth". He is also told that he will be killed by a dead man. Shore's ghost merges with the body of Anne, and a semi-deranged Richard strangles his own wife, believing her to be Shore. Without his beloved Anne, he is struck with guilt and loneliness. Richard consults the Moorish physician and sorcerer Tyrus, who shows him visions of his future, including the prophecy that he will be king. Tyrus is disturbed by Richard's increasingly deranged demeanour. Fearful for the safety of the princes, he informs Sir Jasper, a young aristocrat who is looking after the lads. Jasper plots with his girlfriend, Lady Margaret, to rescue the princes. He manages to get the young Duke of York and his mother free, but he is trapped and captured with the child-king Edward. Lady Margaret, who has been sent to get aid from her father Lord Stanley, is also captured and imprisoned. Richard spares Jasper, because he needs him to negotiate with Stanley, who is withholding his support for the Protector. Richard forces the Archbishop to give up the Duke of York, who has sought church sanctuary in Westminster Abbey with his mother. Aided by his crony, Sir Ratcliffe, Richard then murders the two princes in their beds and proclaims himself king. The ghosts of the princes try to lure Richard to his death from the battlements of the Tower, but he is saved by Buckingham. Buckingham confides in Ratcliffe his doubts about Richard's sanity, suggesting that they should join Lord Stanley. Ratcliffe informs Richard, who has Buckingham tortured to death. Meanwhile, Tyrus helps Jasper to rescue Margaret, but is mortally wounded during the escape. Jasper and Margaret join Stanley to encourage him to topple Richard from the throne. Richard is crowned, but is still haunted by fear. Ratcliffe informs him that Stanley has marched to the village of Bosworth with an army. Richard declares that he will fight. When Ratcliffe learns that Stanley has been joined by the Earl of Richmond, he advises Richard to flee, but the king is convinced of his invincibility. At the Battle of Bosworth Field Richard is eventually left alone on the battlefield after his army has been defeated. The ghosts of his victims appear, and he attempts to fight them. Jasper, Stanley and Richmond watch as Richard swipes at thin air. The king attempts to mount a horse, but is thrown and killed by a battleaxe held by a dead soldier.