Edward II has just become king after the death of his father, and he immediately summons his exiled favorite, Piers Gaveston, to the court. This does not make the nobles of the court happy, as they see Gaveston as basely born and their own influence suffering in light of his.
In particular, Mortimer (Junior) and the Earl of Lancaster mount an offense, taking their complaints to the king. Edward cares not, and happily welcomes Gaveston home. The nobles threaten Edward that he cannot have his minion here, and Edward is astonished at their audacity. Nevertheless, he keeps Gaveston by his side and even strips the Bishop of Coventry, who’d been responsible for Gaveston’s exile, of his property and tokens of office.
Opposition mounts as the nobles gather together with the Archbishop and discuss Edward’s behavior. The Queen also mourns her husband’s preference for Gaveston, and implores them to do something but not to hurt the king.
The nobles draw up a document exiling Gaveston again and force Edward to sign it. He does so reluctantly, knowing he has few options, but whispers to Gaveston that he will figure out how to bring him back.
The Queen is glad Gaveston is gone, but realizes that Edward is now treating her horribly because he is so angry. She decides it would be marginally better if Gaveston were back, and takes her plea to Mortimer. Mortimer, who is romantically interested in the Queen, listens to her and decides she is right—they should bring Gaveston back and simply endure his obnoxiousness if it will calm Edward down. Besides, if Gaveston does not behave, Mortimer tells the others, they can take care of him.
The Queen informs Edward that Gaveston is being recalled. He nearly weeps with joy and embraces her. He then appoints the nobles to high positions and they are confident that things will be better now. Mortimer is the only one who privately grumbles to his father that he is not appeased.
In Act Two, plans are put into place for Gaveston’s return. Edward already starts to show himself distracted, telling his advisors that he does not need to focus on the King of France’s landing in Normandy at the moment. Gaveston arrives and the two men embrace, but without warning, Lancaster and Mortimer draw their swords and proclaim Gaveston a traitor. Mortimer wounds him. Edward screams that they will pay.
Mortimer contents himself that he has done the right thing and he expects the king to do the right thing as well. He asks Edward to help ransom his father who has been taken prisoner by the Scots, arguing that since Edward sent him there it is his responsibility. Edward refuses, and Mortimer hotly denounces him and his false reign.
Edward is furious at the nobles’ behavior, especially Mortimer’s. He is also frustrated with his brother Edmund, the Earl of Kent, who does not seem to be supporting him as he should. He takes two new allies, though, in Spencer Junior and Baldock, men of his niece’s father. He decides to marry Gaveston to his niece and elevate Spencer and Baldock.
The nobles refine their plan to take Gaveston, and even the Queen has to acknowledge it might be the right thing to destroy him since her marriage is so fraught; thus, she tells them where the king and Gaveston are.
The nobles find Gaveston and apprehend him. A message comes from the king asking to see Gaveston one last time before he is put to death, and the nobles scoff that this cannot be the case. Pembroke, however, says he will take this responsibility on.
In Act Three, Spencer counsels Edward to fight the nobles, to which Edward agrees. He sends his wife and their son, Prince Edward, to France to curry favor with the king. Not long after, he learns that Gaveston is dead and subsequently collapses in despair. He vows revenge.
A herald from the nobles arrives and asks Edward to get rid of Spencer and Baldock, and, if he does, he can continue to rule and the conflict will be avoided. Edward refuses.
A major battle commences and most of the nobles are captured. Some are executed, and Mortimer is put into the Tower. Edward is triumphant, and makes sure to seal his revenge against the Queen by sending money to France to turn all the lords against her.
In Act Four, Kent regrets leaving Edward and Mortimer escapes from jail. The Queen has a hard time finding friends in France and no longer takes her husband’s side. She is cheered when she sees Mortimer is out and that Sir John of Hainault has promised to deliver friends and allies to her and the Prince.
Edward thinks that he has triumphed over the Queen and Mortimer, as the Queen has gotten no aid and Mortimer is incarcerated, but he soon learns Mortimer is free. A massive battle takes place and Edward’s side loses.
Edward, Spencer Junior, and Baldock flee to an abbey to seek solace from the Abbot and the monks. Unfortunately, a Mower recognizes them and turns them over. Edward is thrown in a cell and the other two are killed.
In Act Five, Edward is told he must yield his crown. He is reluctant to do so, but concedes when he learns Prince Edward’s claim to the throne will not be honored if he does not resign.
Mortimer and the Queen, who are now sexually and politically involved, put Matrevis and Gurney in charge of Edward, telling them to take him to Killingworth and treat him abominably. Prince Edward is made King Edward III after his father’s resignation, and Kent is made his Protector.
Kent, who despises Mortimer and realizes he should have stayed loyal to Edward, tries to rescue his brother but is captured and brought before Mortimer, the Queen, and Edward III. Mortimer orders him to be killed but Edward III argues for his life. Mortimer now takes the role of Protector and Kent is sent to prison. Mortimer knows he must get rid of Edward or his position will be more and more tenuous. He engages the services of Lightborn, an assassin.
Edward languishes in deplorable conditions in his dungeon, bemoaning his fate. He is not long for the world, though, because Lightborn soon arrives, smoothly lying to the former king that he is here to comfort him, not harm him. Regardless of his words, he stabs Edward with a red-hot poker and kills him. Gurney kills Lightborn and flees.
Matrevis comes to the court where he tells Mortimer and the Queen Edward is dead. Their jubilance is short-lived, for Edward III learns of this as well and is preparing to avenge his father. He and his lords approach Mortimer and the Queen and Edward III accuses Mortimer of treason and murder, showing Mortimer his own words for Gurney which he’d been made privy to. Mortimer knows Gurney has betrayed him and asks for no sympathy.
Edward III announces Mortimer will be beheaded and his head will rest atop his father’s hearse. He orders his mother sent to the Tower to await trial. At the end of the play, Edward III weeps over his father’s hearse.