The play begins with the brief appearance of three weird sisters who plan to meet Macbeth, and then moves to a military camp. The Scottish King Duncan hears the news that his generals, Macbeth and Banquo, have bravely defeated their enemies. Duncan orders the execution of the traitorous Thane of Cawdor and arranges for the Thane's title to be passed to the valiant Macbeth.
Macbeth and Banquo encounter the weird sisters who prophesy that Macbeth will be made Thane (a rank of Scottish nobility) of Cawdor and eventually King of Scotland. They also prophesy that Banquo will beget a line of Scottish kings, although Banquo will never be king himself. The weird sisters vanish, and Macbeth and Banquo treat their prophecies skeptically until some of King Duncan's men come to thank the two generals for their victories in battle and to tell Macbth that he has indeed been named Thane of Cawdor. The first prophecy has come true. Macbeth is intrigued by the possibility that he will be crowned king, but he is uncertain what to expect. King Duncan then thanks Macbeth for his part in the battle and announces that the next king will be his son, Malcolm. Macbeth writes to his wife, Lady Macbeth, telling her all that has happened.
Lady Macbeth reads the letter and decides that Duncan should be murdered in order to obtain the corwn for Macbeth. She puersuades Macbth to kill the king that very night. He meets Banquo on his way to Duncan's chamber and reasserts his loyalty to the king. Then, despite his doubts, including the vision of a bloody dagger, Macbeth goes to Duncan's room and kills him.
Lady Macbeth, having drugged Duncan's guards, is now bolder than ever while Macbeth's conscience is disturbed. She takes Macbeth's bloody daggers to leave them as gruesome evidence with Duncan's guards. When Duncan's death is discovered, Macbeth kills the guards out of fabricated rage at their apparent crime, adn the crown passes to him. Duncan's sons, Malcolm and Donalbain, flee, fearing Duncan's murderers want them dead as well.
Fearing the weird sisters' prophecy that Banquo's heirs will seize the throne, Macbeth hires murderers to kill Banquo, but they fail to kill his son, Fleance, who escapes into the nights. Just before the feast, Macbeth is told of Fleance's escape and becomes furious. At the feast that night, Macbeth sees Banquo's ghost and raves fearfully, startling his guests. Lady Macbeth dismisses the company and tries to calm Macbeth who vows to revisit the "weird sisters" to see what prophecy is yet in store.
Macbeth's kingship incites increasing resistance from his nobles and subjects. They learn that Macduff, a Scottish nobleman who opposed Macbeth, has fled to England to join Malcolm. Macbeth goes to visit the weird sisters. They present him with further prophecies: he must beware of Macduff; he cannot be harmed by any man born of woman; and he will be safe until Birnam Wood comes to Dunsinane Castle. Macbeth is then relieved and feels secure. When he learns that Macduff has fled to England, Macbeth orders that Macduff's castle be seized and his family murdered.
In England, Prince Malcolm, Duncan's son, has succeeded in raising an army. Malcolm becomes convinced of Macduff's loyalty. When news of his family's execution reaches him, Macduff is stricken with grief, vows revenge, and joins Malcolm to challenge Macbeth's forces.
Lady Macbeth, meanwhile, is going mad. She becomes plagued with fits of sleepwalking in which she bemoans when she believes to be bloodstains on her hands. She recalls images of the murders of Duncan, Banquo and Lady Macduff. Macbeth's opponents arrive at Birnam Wood. Macbeth, waiting at Dunsinane, is told of their advances but is certain that the weird sisters' prophecies guarantee his invincibility. Still, he armors himself and, as he prepares for battle, learns of Lady Macbeth's descent into madness.
Malcolm's armies cut boughs from the trees of Birnam Woods to mask their numbers as they advance on Dunsinane. Macbeth receives news that Lady Macbeth has died and then is struck numb with fear when he learns that Birnam Wood is indeed coming to Dunsinane, fulfilling half of the weird sisters' prophecy.
In the battle the English forces gradually overwhelm Macbeth's army and castle. Macbeth fights gamely, but finally encournters the vengeful Macduff, who declares that he was not "of woman born" but was instead "untimely ripped" from his mother's womb. Though he now realizes that he is doomed, Macbeth continues to fight until Macduff kills and beheads him. With the tyrant dead, Malcolm is proclaimed King of Scotland and declares his benevolent intentions for the country.