King Lear, the king of Britain, old and irritable, decides to divide his kingdom among his three daughters, according to the depth of love each one has for him. Although Goneril (married to the noble Albany) and Regan (wife of the violent Cornwall) excessively proclaim their love for him, the youngest, Cordelia, contemptuously says: 'I cannot bring my heart / to my lips.'

Angered, Lear disinherits her, punishing Kent, who defended her, but the King of France takes her without a dowry to be his queen. Lear gives her share to her sisters and proposes to stay alternately with them, accompanied by his retinue of 100 knights. Edmund, the illegitimate son of Gloucester, fosters disagreements between his legitimate brother Edgar and their father.

Kent, disguised, returns to serve his master Lear. Goneril greets Lear with hatred. Cursing her, Lear departs for Regan. At the same time, Regan and Cornwall arrive at Gloucester's castle, while Edgar has fled. Regan proves to be even harsher than Goneril.

Believing that madness will prevail, Lear wanders into the night storm where he is found by loyal Kent. Gloucester, defying the anger of the two sisters and Cornwall, finds refuge for them in a hut (where Edgar is disguised) and urges Kent to lead the endangered king to Dover.

Returning to his castle, Gloucester is insulted and brutally blinded by Cornwall (sight and blindness are two themes of the play), who is then killed by a servant. Edgar, still disguised and unknown to his blind father, embarks with him for Dover. There is a strange encounter between the mad King and the blind man.

Shortly thereafter, Cordelia, who has returned from France, reconnects with Lear. In a battle that the French forces lose, they are captured and sent to prison where, under Edmund's instructions, they are to be killed. But Edmund—who has deceived both Goneril and Regan—is killed by Edgar (as an unnamed knight) in a duel.

Goneril poisons Regan and then stabs herself. Cordelia is hanged in prison. Lear takes her 'dead in his arms' and within minutes he dies as well. 'The miracle is that he endured so long / he lived abusively.'

At Albany's wish, Edgar will take over the kingdom, but Kent will follow Lear: 'my master calls me... and I must not say no.' King Lear is a harrowing, painful journey of the spirit and the mind.