The porter, the discovery, the flight

The knocking that ended the previous scene continues. The porter, drunk and hung over, drags himself to the gate. His monologue is the play's only sustained comic stretch. He pretends to be the porter of hell. He admits, in his head, a farmer who hanged himself on the expectation of a good harvest; an equivocator who could swear in both scales; an English tailor who stole cloth out of a French hose. He opens the gate. Macduff and Lennox enter; the porter jokes about how drink provokes lechery — "it provokes the desire, but it takes away the performance."

Macbeth, in his nightgown, comes out as if newly woken. Macduff goes to wake the king and returns within thirty seconds shouting: "O horror, horror, horror! Tongue nor heart cannot conceive nor name thee!" He rings the alarm; the castle wakes. Banquo, Malcolm, Donalbain, Lady Macbeth, all gather. Macbeth, performing horror, announces that in the heat of his loyalty he has killed the two grooms whose daggers were lying on them. The killing is dramatically a mistake; Macduff in particular notices. Macbeth gives a speech about the impossibility of restraining love and grief. Lady Macbeth faints — whether real or staged, the play does not say.

Malcolm and Donalbain, alone aside, work out their position quickly. They have lost their father; they have no allies; the killer is still in the castle. Donalbain delivers the line: "where we are, there's daggers in men's smiles. The near in blood, the nearer bloody." They will flee — Malcolm to England, Donalbain to Ireland. Their flight, when discovered, will be turned into evidence against them: the rumour will be that they hired the grooms and ran. Macbeth, by the end of the scene, has been positioned for the throne. The next time we see him, he will be king.