Contains spoilers for this episode.
With Richard IV away on a crusade, Edmund imagines that he can share the government with Harry. His brother keeps the important work and leaves him chores, including drains and royal portraits. When preparations begin for the king's return, Edmund must organise the entertainments. The arrival of the swaggering Scottish commander Dougal McAngus adds a personal insult when Harry awards him lands that already belong to Edmund.
Edmund recruits McAngus for a court play and substitutes real knives for the theatrical weapons, expecting the performance to dispose of his rival. He abruptly tries to save him when McAngus mentions letters suggesting that Harry's parentage could exclude him from the succession. Edmund abandons the entertainment in favour of a public announcement, hoping to remove his brother and inherit from a father reportedly facing thousands of enemies with a fruit knife.
Richard returns alive at exactly the wrong moment, and Harry notices a worse flaw in Edmund's evidence. The letters were written after Harry's birth, but before Edmund's, putting the younger prince's legitimacy in question instead. Edmund destroys them and accuses McAngus of forgery. A challenge to a duel ends with Edmund disarmed and begging for mercy. McAngus spares him, but their apparent friendship lasts only until Edmund arranges the cannon accident that Baldrick originally suggested.