It is approximately 1485 in England and Richard of Gloucester is incensed that his brother King Edward has taken the throne after numerous civil wars fought between their family (the House of York) and the House of Lancaster. Richard feels excluded from everyone's peacetime celebrations because he was born unattractive, has a hunchback, and lacks love. Instead of frolicking, he has contrived a plot to make himself king. He's turned King Edward against their brother George of Clarence (next in line for the throne) by leading Edward to believe a prophesy that he'll be murdered by a family member with a ‘G' in his name. Yet, when Richard meets Clarence on his way to prison, he pretends to be outraged at Clarence's circumstance and promises to go plead Clarence's case to Edward. On the way Richard meets Lady Anne in mourning for her father-in-law Henry VI and her husband Edward of Westminster, the king and heir to the throne before Richard killed them both. Richard is determined to marry her to advance his rise to the throne and, though Anne understandably detests him, he manages to sweet-talk her into accepting his ring. Alone, Richard gloats at his coup.
Meanwhile, Queen Elizabeth is worried because King Edward is sick and she fears Richard, who hates her and her allies, will take power. At the palace, she and Richard bicker until Queen Margaret, the former Queen who was supposed to be banished, steps out and begins cursing everyone for depriving her of her husband Henry VI, son Edward of Westminster, and rightful place on the throne. Everyone bands against her. She curses each person present, saving the worst for Richard. She prophesies that Richard will ruin everyone's lives.
Richard secretly arranges Clarence's murder and, when King Edward decides to free Clarence, Richard pretends to be just as sad as everyone else at the mix-up. King Edward dies soon after and his son Edward Prince of Wales is brought to London to be crowned the new king. Meanwhile, Richard and his sidekick Buckingham plot to crown Richard instead. They capture Queen Elizabeth's relatives, Earl Rivers, the Marquis of Dorset, and Lord Grey and plan to execute them. That night, Lord Stanley has a dream foreboding Lord Hastings' beheading by Richard, but fails to convince the trusting Hastings to run away. Sir William Catesby tries to win Hastings over to Richard's plot but he refuses and, indeed, Richard soon finds an excuse to have Hastings beheaded. Richard and Buckingham spread the news of Richard's impending coronation with the help of the Lord Mayor, but receive a stunned lack of enthusiasm from the public. To win favor, Richard and Buckingham stage a scene in which Richard acts humble and religious and repeatedly declines the offer of the crown, accepting it only at Buckingham's insistence.
Richard is officially crowned. He imprisons King Edward's sons and orders Buckingham to kill them. When Buckingham hesitates, Richard turns against him and finds another hit man. Fearing that he himself will be the next to be killed by Richard, Buckingham flees and starts to raise an army against Richard. Richard plans to imprison Anne and marry King Edward's daughter to secure his throne. He intercepts Elizabeth in mourning for her sons and, though she loathes him, Richard eventually manages to convince her to coax her daughter into marrying Richard (or so he thinks).
Reports arrive that the Earl of Richmond, a member of the house of Lancaster, approaches England with troops, aiming to usurp Richard's throne. Richard sends Stanley off to raise troops for him, threatening to behead Stanley's son if he fails to return. Stanley secretly arranges to side with Richmond and notes that Elizabeth is eager to give her daughter's hand to Richmond. A messenger reports that Buckingham's army has scattered and that Buckingham is captured. Before execution, Buckingham repents his sins, feeling his death to be deserved. Richard marches off with troops to fight Richmond.
Richmond proves himself a generous and conscientious leader by treating his army well. The night before the battle between Richard and Richmond, the ghosts of all Richard's victims rise into the night and hurl curses at Richard while giving Richmond their blessing. The next day, Richard is defeated and killed and Richmond takes the crown, resolving to end the Wars of the Roses and establish peace by marrying young Elizabeth, the daughter of King Edward, uniting the houses of York and Lancaster forever.