King Henry (Bolingbroke) asks if anyone has had news of his son, whom he hasn't heard from for three months. He calls him a "plague" hanging over the new kingdom and orders a search of the taverns, where the prince is known to hang out with criminals.
Henry Percy replies that he saw him two days ago and told him about the combat trials at Oxford. He says the prince made a crack about going to the brothels instead.
King Henry hopes his kid will grow up someday.
Aumerle walks in, dazed, and asks where the king is. King Henry asks him why he's acting all crazy. Aumerle says he wishes to speak to the king alone. Henry orders everyone else out.
Aumerle begs for forgiveness. King Henry asks whether the offense is "intended" – that is, still in the planning stages, or done. If only intended, he'll forgive him. Aumerle asks for permission to lock the door so that no one can enter until he finishes his confession.
Henry allows this. Aumerle locks the door just as York starts banging on the door from outside, yelling to King Henry that he's locked in with a traitor.
Henry draws his sword on Aumerle, who tells him he has no reason to fear. York yells to the king to open the door. King Henry unlocks it and asks York to tell him what's going on. York shows him the paper Aumerle had around his neck.
Aumerle reminds the king of his promise to forgive him for an intended offense and says he repents.
York calls his son a villain and asks the king not to take pity on him.
King Henry, shocked, praises York's honesty and calls Aumerle a "deadly blot." York says his son has spent his honor with his shame. He insists that by allowing his son, a traitor, to live, the king would be killing him, an honest man.
The Duchess arrives and begs King Henry to allow her inside. Henry tells Aumerle to let her in, and York warns him again that by letting Aumerle live, the rest of the body will be infected.
The Duchess addresses the king. York asks her if she wishes to raise another traitor. She kneels in front of the king and says she will walk forever on her knees unless he pardons her son. Aumerle kneels too, joining his prayers to hers. York kneels against them both, asking for Aumerle's punishment.
The Duchess accuses York of false prayers and hypocrisy. Henry tells her to stand up. She tells him to say "pardon" first, and then she'll stand.
York asks the king to say "pardonne-moi," a polite refusal. The Duchess points out that Henry hates French – they should just talk to the king in plain English.
Henry finally pardons Aumerle, but orders the destruction of the rest of his group of traitors.