Macbeth and Banquo encounter three witches who prophesy that Macbeth will become King of Scotland. When Macbeth is named Thane of Cawdor, as the witches predicted, he begins to believe he will be king. Lady Macbeth convinces Macbeth to murder King Duncan when he stays at their castle. Macbeth kills Duncan and becomes king, but grows increasingly paranoid and tyrannical, orchestrating more murders to protect himself from threats to his power. He is eventually killed in battle by Macduff, fulfilling the final witch's prophecy.