Act 1: The play takes place in Scotland. Duncan, the king of Scotland, is at war with the king of Norway, and as the play opens, he learns of Macbeth's bravery in battle against a Scot who sided with Norway. At the same time, he hears of the treachery of the Thane of Cawdor, who was arrested. Duncan decides to give the title of Thane of Cawdor to Macbeth.
Macbeth and Banquo, traveling home from the battle, meet three witches, who predict that Macbeth will be Thane of Cawdor and king of Scotland, and that Banquo will be the father of kings. The witches disappear, and Macbeth and Banquo meet up with two nobles who inform them of Macbeth's new title. Hearing this, Macbeth begins to contemplate murdering Duncan in order to realize the witches' second prophecy.
Macbeth and Banquo meet up with Duncan, who tells them he is going to pay Macbeth a visit at his home at Inverness. Macbeth rides ahead to prepare his household. Meanwhile, Lady Macbeth receives a letter from Macbeth informing her of the witches' prophesy and Macbeth's subsequent new title. A servant appears and tells her of Duncan's approach. Energized, she invokes supernatural powers to strip her of her feminine softness and prepare her to murder Duncan. When Macbeth arrives at Inverness, Lady Macbeth tells him that she will take care of all the details of Duncan's murder.
Duncan arrives at Inverness, and Lady Macbeth greets him. Macbeth fails to appear, and Lady Macbeth goes to find him. He is in his room, contemplating the weighty and evil step of killing Duncan. Lady Macbeth taunts him, telling him he will only be a man when he kills Duncan, and that she herself has less softness in her character than he does. She then tells him her plan for the murder, and Macbeth accepts it: they will kill him while his drunken bodyguards sleep, then plant incriminating evidence on the bodyguards.
Act 2: Macbeth has a vision of a bloody dagger floating before him and leading him to Duncan's room. When he hears Lady Macbeth ring the bell to signal the completion of her preparations, Macbeth follows through with his part of the plan and leaves for Duncan's room.
Lady Macbeth waits for Macbeth to finish killing Duncan. Macbeth enters, still carrying the bloody daggers. Lady Macbeth again chastises him for his weak-mindedness and plants them on the bodyguards herself. As she does so, Macbeth imagines that he hears a voice saying "Macbeth will sleep no more." Lady Macbeth returns and assures Macbeth that "a little water clears us of this deed."
At the gate the porter pretends that he is guarding the door to hell. The thanes knock at the gate, and Macduff discovers Duncan's body when he goes in to wake him up. Macbeth kills the two bodyguards, supposedly in a fit of grief and rage, when they are discovered with the bloody daggers. Duncan's sons Malcolm and Donalbain, fearing that their lives are in danger, flee to England and Ireland; their flight brings them under suspicion of conspiring in Duncan's death, and Macbeth is crowned king of Scotland.
Act 3: Macbeth hires two murderers to kill Banquo and his son Fleance in an attempt to thwart the witches' prophesy that Banquo will father kings. Lady Macbeth does not know of his plans, and he will not tell her. A third murderer joins the other two on the heath, and the three men kill Banquo. Fleance, however, escapes.
Macbeth throws a feast on the same night that Banquo is murdered, and Banquo's ghost appears to him, sending him into a frenzy of terror. Lady Macbeth attempts to cover up for his odd behavior, but the party ends up dissolving as the thanes begin to question Macbeth's sanity. Macbeth decides that he must revisit the witches to hear more of the future.
Meanwhile, Macbeth's thanes begin to turn from him, and Macduff meets Malcolm in England to prepare an army to march on Scotland.
Act 4: The witches show Macbeth three apparitions that tell Macbeth to fear no man born of woman, and warn him that he will only fall when Birnam Wood comes to Dunsinane castle. Macbeth takes this as a prophecy that he is infallible. When he asks the witches if their prophesy about Banquo will come true, they show him a procession of eight kings, all of whom look like Banquo, the last holding a mirror to signify the reign of James I, the Stuart king for whom Shakespeare wrote this play.
Malcolm tests Macduff's loyalty by confessing to multiple sins and ambitions. When Macduff proves loyal to him, the two plan the strategy they will use in attacking Macbeth. Meanwhile, Macbeth murders Macduff's wife, whom he has deserted, along with all his children.
Act 5: Lady Macbeth sleepwalks and reveals her guilt to a watching doctor as she dreams that she cannot wash the stain of blood from her hands. Macbeth is too preoccupied with battle preparations to pay much attention to her dreams, and is angry when the doctor says he cannot cure her. As the castle is attacked, Lady Macbeth dies (perhaps by her own hand). When Macbeth hears of her death, he comments that she should have died at a different time, and muses on the meaninglessness of life. However, he reassures himself by remembering the witches' predictions that he will only fall when two seemingly impossible things occur.
Meanwhile, the English army has reached Birnam Wood, and in order to disguise their numbers, Malcolm instructs each man to cut a branch from a tree and hold it in front of him as they march on Dunsinane. Witnessing this, Macbeth's servant reports that he has seen something impossible Birnam Wood seems to be moving toward the castle. Macbeth is shaken but goes out to fight nonetheless. During the battle outside the castle walls, Macbeth kills Young Siward, the English general's brave son. Macduff then challenges Macbeth. As they fight, Macduff reveals that he was not "born of woman" but was "untimely ripped" from his mother's womb. Macbeth is stunned but refuses to yield to Macduff. Macduff kills him and cuts off his head. Malcolm is proclaimed the new king of Scotland.