Back at Dunsinane, Macbeth is getting a little overconfident. Dunsinane is well fortified, and he thinks he can wait out any attempt at a siege. The feeling is short-lived, though. He finds out that his wife has died, and that Birnam Wood is, in fact, marching to Dunsinane. Or, at least, thousands of soldiers carrying tree branches are. Macbeth vows to fight to the death.
Everyone has arrived at Birnam Wood, and they’re ready to march on Dunsinane. Malcolm fulfills the witches’ vision by commanding that each soldier carry a bough from the trees of Birnam Wood so that they’ll be concealed as they approach Dunsinane.
Macbeth gets a whole heap of bad news in this scene. He learns from the doctor that his wife is not well, and that there’s nothing the doctor can do to help her. Plus, he hears that ten thousand English troops and a whole lot of Scottish ones have gathered together to take him down. He prepares to fight.
Scottish troops, led by Angus, Lennox, and other soldiers, are headed toward Birnam Wood. There, they plan to meet up with Macduff, Malcolm, and their English troops. They all discuss Macbeth’s horrible leadership and the fact that he’s clearly in this for himself, rather than for Scotland. He’s just not king material, the Lords decide, and they’ve got to get him off the throne.
Back at Dunsinane, a doctor and a gentlewoman are spying on Lady Macbeth. She’s been acting weird lately. Sure enough, she enters the scene sleepwalking and talking to herself. While the doctor and the gentlewoman look on, Lady Macbeth frantically tries to rub an invisible stain from her hand, all while ranting and raving about her husband, guilt, and, of course, blood. At this, the doctor and the gentlewoman realize that Lady Macbeth has been keeping some pretty evil secrets, and that’s not something the doctor can help her with. She needs a priest, not a medical professional.
Macduff meets up with Malcolm in England and the two make plans for how to overthrow Macbeth and take back their kingdom. Malcolm’s a little suspicious of Macduff though, so he attempts to suss out whether the thane is loyal to Scotland, or just in it for himself. After Macduff proves himself loyal, the two of them join up with ten thousand troops to take down Macbeth. Ross arrives, bringing news that Macduff’s family has died, but that if he returns to Scotland, there are a lot of folks who would happily join with him to fight Macbeth.
Macduff’s wife, Lady Macduff, questions Ross about her husband fleeing to England. She doesn’t understand why he would leave his family defenseless at a time like this. Ross tries to reassure her, but no sooner does he leave than a messenger arrives to tell Lady Macduff and her son to run for their lives. But it’s too late—the murderers have arrived, and they kill her son. She flees, the murderers hot on her heels.
Macbeth meets up with the witches, who are busy making potions and casting spells. He tells them he wants to learn more about his future. They tell him three key things: He should keep an eye on Macduff. He won’t face any harm from anyone “of woman born." He won’t be conquered until Birnam Wood marches to Dunsinane. Macbeth thinks this is all good news—after all, since when can forests march? And Macduff is definitely of woman born, right? Still, he thinks it’s a good idea to kill Macduff anyway, just in case.
Lennox and another lord are talking politics. For his part, Lennox is pretty suspicious of Macbeth and doesn’t believe the new king’s version of recent events. We learn that Macduff has fled to England, where he’s joined up with Malcolm. They’re trying to get the King of England on board with a plan to overthrow Macbeth. The unnamed Lord also tells Lennox that Macbeth has heard these rumors and is prepping for all out war.
