Lear, King of Britain, decides to abdicate and divide his kingdom between his three daughters. When his youngest and favourite, Cordelia, refuses to make a public declaration of love for her father, Lear disinherits her. The Earl of Kent, Lear's loyal follower, is banished for daring to defend her. The kingdom is then divided between Lear's two elder daughters, Gonerill and Regan, and their husbands. Cordelia, disowned by her father, is married off without a dowry to the King of France.

Gloucester, deceived by his bastard son Edmund, disinherits his legitimate son, Edgar, who is forced to go into hiding to save his life.

Lear, now stripped of his power, quarrels with Gonerill and Regan about the conditions of his lodging in their households. Enraged, he goes out onto the heath in a terrible storm, accompanied by his Fool and by Kent, who has disguised himself as a servant called Caius.

There they encounter Edgar, disguised as a mad beggar, Poor Tom of Bedlam. Gloucester is betrayed by Edmund and captured by Regan and Cornwall, who gauge out Gloucester's eyes.

King Lear is taken to Dover, where Cordelia has landed with a French army. The blind Gloucester meets, but does not recognise Edgar, who leads him to Dover. Lear and Cordelia are reconciled but in the ensuing battle they're captured by the sisters' forces.

Gonerill and Regan both fancy themselves to be in love with Edmund and compete for his favour. Discovering this, Gonerill's husband Albany forces Edmund to defend himself against the charge of treachery. A knight appears to challenge Edmund and, after fatally wounding him, reveals himself to be Edgar. News arrives that Gonerill has poisoned Regan and then committed suicide. Before dying, Edmund reveals that he has ordered the deaths of Lear and Cordelia. He attempts to reprieve the order but it is too late.