Arthur stands on the walls of the castle in disguise. He decides he will jump off the wall in order to escape. No one will recognize the body if he dies, he decides, and it is as good to die in England as to escape. He jumps and dies.
Salisbury and Pembroke enter with Lord Bigot. The lords discuss their imminent meeting with Louis. The Bastard enters to speak on behalf of King John. Salisbury tells him to return to the king with news that they no longer honor him. They exchange barbed comments, until Salisbury sees Arthur's body. Each of the lords is horrified to see what they believe John has ordered and have a hard time imagining the vile nature of one who would order a young man killed in such a manner.
Hubert enters and announces his message from the king: Arthur is alive! Salisbury angrily accuses him of being a murderer and draws his sword. The Bastard tries to keep the peace, and Bigot demands to know who killed Arthur. Hubert says he had last seen him alive but a short while ago. The lords don't believe him and depart to join the Dauphin's forces.
The Bastard tells Hubert that he will certainly be damned if he knew of the plan to kill Arthur thus. Hubert insists Arthur was alive when he left him. The Bastard tells Hubert to carry the body away and ruminates that he can't tell what is the truth. How easily Hubert can lift and carry the hopes of England! Much confusion awaits, now that the king must do battle with the foreign army and with his own turned lords. They rush off to the king.
It is a mystery why Arthur decides to jump off the walls of the castle rather than finding a less deadly method of escape, an awkward detail that contributes to King John's low reputation among Shakespeare's works. But he dies, and when the nobles find him, they assume he has been assassinated. Hubert arrives to report that John has not had Arthur murdered, only to find the lords furious at him for killing the boy. The accidental and unwitnessed death of Arthur is again held to be John's fault and Hubert's doing.
John thought he would no longer be suspected of ordering Arthur's death because Hubert broke his oath and refused to kill Arthur. It was an accident, a failing of Hubert's faith, that let John try to exonerate himself. Yet another accident caused Arthur's actual death, and neither John nor Hubert can prove to the lords they didn't kill Arthur. John hoped he could win the nobles back, but instead their departure is finalized.