The Queen Mother and the lords await the return of King Edward I from his journey to the Holy Land. While the Queen Mother delivers a speech praising her son, the lords go to meet him on the road. King Edward, his brother Edmund, wife Eleanor, stepdaughter Joan and other lords enter and are greeted joyfully by the Queen Mother, who even faints out of happiness. The king is in great joy, despite hearing of the deaths of his father, son and uncle while he was away, and delivers a patriotic speech, praising England. He then says he will found a college for his soldiers in their honor, and all present pledge to donate large sums to it, with the queen giving the most. The king then plans his coronation ceremony for December (since he was a way for several years after his father's death), but Eleanor urges him to delay it until the spring so she has time to get the right clothing, which Edward agrees to, before departing with the lords. Queen Eleanor then discusses with her daughter Joan how she will be a great queen. Joan reminds her not to be too lavish and to remember the common people.
Lluellen, Prince of Wales, talks of the return of his love Eleanor with fellow Welshmen Owen ap Rice and Rice ap Meredith. The Welshmen talk of war against the English but worry that King Edward will return before they are able to fully prepare. Luckily, Lluellen has his brother David as a spy at court. Friar Hugh ap David, his novice, Jack, and his mistress, Guenthian, enter, and the friar attempts to seduce the woman. A drawn-out and comical argument then ensues between Friar Hugh and the Welsh that sees them mock the friar for his love of women (despite his vow of chastity), who then, in turn, demands that they leave him to his pleasure. The friar finally calms himself when he discovers who Lluellen is, and the novice returns with a harpist/prophet, who then tells of how Lluellen will defeat King Edward in battle and become King of England. Lluellen dismisses these claims at first but then seems to be more receptive, along with the others. Guenther then arrives to inform Lluellen that King Edward has returned to England and has taken Eleanor captive. Lluellen is furious by this news and vows to make war against the English.
After his coronation ceremony, King Edward speaks with a group of Scottish noblemen, including John Balliol, and agrees, as Lord of Scotland, to choose a king for them. The king chooses Balliol, and all present do homage to him as the new King of Scotland. Queen Eleanor praises her husband in a speech, and Edward prepares to do battle against the Welsh, who he knows are up in arms against him.
Lluellen and Rice meet with David, Lluellen's brother, to discuss their strategy against the English. David, who is a spy at King Edward's court, is to somehow infiltrate the council to discover the plan against the Welsh. Lluellen, who only seems interested in winning back Eleanor, is happy when David suggests that the Welsh should pretend to take him captive in hopes that King Edward will return Eleanor in exchange for his release.
The English and Welsh engage in battle, and Edward reprimands Lluellen for his disloyalty. David is then brought out as prisoner, and the king accepts, at first, that he will be a casualty of war. The Welsh then begin to torture him in the king's presence, forcing Edward to agree to a truce in order to win back the man he believes, wrongly, to be his ally. Lluellen agrees to a truce, but Edward must release Eleanor from captivity, which he willingly does, much to the chagrin of Lord Mortimer (who has fallen in love with her). This, however, is not enough for Lluellen, and he claims that Edward must also allow the Welsh to live in peace under the command of a native Welshman and to be pardoned of their offenses against the king. Edward agrees to these terms, and the two sides meet in peace, with Eleanor being returned to Lluellen. Mortimer ends the scene with a lament over his lost love.
Queen Eleanor, Joan and the Earl of Gloucester travel through Wales on their way to the queen's new home (since the king wants the pregnant Eleanor to give birth to their son in Wales, so he will be a native Welshman and therefore eligible to rule over the country under the terms of the truce). As the pregnant queen complains of the heat and the uncomfortable conditions, Joan and Gloucester exchange loving words, prompting Eleanor to suggest a marriage between the two. King Edward then arrives to check on his wife, who delivers a cold and bitter response, going so far as to slap him at one point. The king, however, is not upset by this instance and even jokingly says that men must always obey their wives or face the consequences. Eleanor says she is not feeling well, and the king claims that anyone who informs him of the birth of a son will be well rewarded.
After Mortimer peacefully departs from the presence of Lluellen and his allies, the Welsh reveal their true intentions. They will once again rebel against King Edward, despite the truce, and they compare themselves to Robin Hood-like figures. Mortimer overhears the conversation and vows to take revenge on the Welsh and win back Eleanor.
Lluellen and the Welsh act in their Robin Hood personae and drop hints that they will soon be at war with the English once again. When Lluellen and Rice depart to search the camp for spies, the friar does his best to seduce Lady Eleanor, much to the chagrin of Mortimer, who is there disguised as a potter, leading the two men to fight. Lluellen and Rice return and force the men to fight again for their own amusement. The scene ends with Mortimer regretting not informing Eleanor who he is.
King John Balliol of Scotland tells his lords of how they will shake off the tyrannical control of England. He gives Lord Versses an ultimatum: throw defiance at King Edward or be hanged. Versses reluctantly agrees to betray the English king.
King Edward (who is first informed that Mortimer is not present because he is in the process of attempting to woo Lady Eleanor) and the lords go to visit Queen Eleanor, who has just given birth to a son, Prince Edward, at her child bed. The king is overjoyed over the birth of his son and creates him Prince of Wales. Also, the queen asks permission for her daughter Joan to marry Gloucester, which the king readily grants. A group of Welsh nobles arrive to pay homage to the new prince and to present him with a mantle as a gift, which the king wholeheartedly accepts and the queen, in the same fashion, rejects. The queen then begins to act erratically, causing the king, who still seems to have a great amount of patience with his wife, to leave. Gloucester and Joan prepare for their wedding festivities.
The novice and his party serenade the queen with music to celebrate the birth of the prince.
The scene begins with the christening of Prince Edward and the marriage of Joan and Gloucester, both of which are highly celebrated by all present, and the king then presents his newly christened son to the queen, who receives him thankfully and congratulates her daughter on her marriage. As the celebration continues, Versses arrives from the Scottish court and delivers the message to Edward that King John of Scotland is in rebellion against him and has set up camp at Berwick, an English city. The king asks Versses to deliver a message back to Balliol, informing him that his rebellion shall soon be put down.
Friar David lays down a scheme to deceive a farmer out of his money. When the farmer (who is also the receiver for St. Francis) arrives, it is David who gives him money. The Welsh then arrive with a number of prisoners, followed shortly by King Edward, David and, once again, the farmer, who is acting as their guide. This time, the friar cons the farmer out of an even larger sum of cash then he had given before, forcing him to return to his master empty-handed. The friar then informs the king that he must pay half of his cash to Lluellen as a toll. King Edward does not take this insult kindly, and he and Lluellen fight. David then goes to his brother's rescue, while Mortimer, still disguised as a potter, goes to that of the king. Both the king and Lluellen are stunned at the respective betrayals they have just experienced, but it is agreed that they will exchange prisoners (David has Mortimer and the king Lluellen) and depart.
King Balliol delivers a speech to his lords, championing the Scots for liberating themselves from the English. Versses then returns from the English court, bringing a rope and halter in mocking fashion from King Edward. Balliol is furious at this gesture and has Versses arrested on the spot.
The scene begins with Edmund Crouchback (King Edward's brother) announcing to Gloucester that his wife Joan has died. King Edward then informs all that his wife, Queen Eleanor, has passed away. A messenger then arrives and informs the king that Balliol and the Scots are threatening to invade Northumberland, and the king, despite his sorrow, sets off to fight his enemies. Gloucester ends the scene with a sad lament for his wife.
Mortimer viciously pursues the rebels.
Lluellen retreats from the English, and his brother David informs him of the disadvantage they are at before they part for the last time. English soldiers arrive and slay Lluellen with a pikestaff. Though they are sorrowful over the death of such a noble man and agree to bury his body, they all agree that his head must be brought to the king.
Friar Hugh laments his part in the rebellion against King Edward and says he will hang himself.
Mortimer comforts Lady Eleanor, who is upset over Lluellen's death, and says that she shall have his love to make up for the Welshman's death. Friar Hugh then begs Mortimer to provide him with another master, since his has perished, and the earl promises to place the friar in the service of the king, before announcing a full pardon for all the rebels that declare allegiance to the king.
King Edward enters with John Balliol as his prisoner and reprimands the Scottish king for his rebellious actions. In the end though, Edward agrees to let him live in exchange for giving up the Scottish crown. A messenger then enters and delivers news that Lluellen is dead, much to the king's happiness.
Mortimer, the friar, the novice and the harper/prophet all accompany David to his execution, which he accepts willingly. All the men wonder at how the harper's prophecy has come true and that Lluellen is wearing a crown (of lead), which his head is impaled on.