Spencer Junior and Baldock, members of the household of the late Earl of Gloucester, are seeking a new nobleman to join up with. Spencer has already decided that he'll join Gaveston as "his companion, for he loves me well, / And would have once preferred me to the king." Baldock says Gaveston is banished, but Spencer has heard otherwise: "even now a post came from the court / With letters to our lady from the king, / And as she read, she smiled, which makes me think / It is about her lover Gaveston." (The lady referred to, the notes tell us is Margaret de Clare, the king's niece.) Baldock has been her tutor, and Spencer urges him to become a courtier: "You must be proud, bold, pleasant, resolute, / And now and then stab as occasion serves." The lady herself enters, reading a letter from Gaveston announcing his return and one from the king asking her to come to the court. She sends Baldock to order her coach and tells Spencer of the good news.
Edward, attended by the queen, Lancaster, Mortimer, Warwick, Pembroke and Kent, is anxiously awaiting Gaveston's arrival. Meanwhile, Mortimer informs Edward that "The King of France sets foot in Normandy," to which the king replies, "A trifle. We'll expel him when we please." But in conversation with Mortimer and Lancaster, they reveal to the king their scorn for Gaveston, which angers him: "They love me not that hate my Gaveston." The queen tries to calm him, while Mortimer asks the other nobles, "If in his absence thus he favours him, / What will he do whenas he shall be present?"
They don't have long to wait, because Gaveston enters immediately to an effusive welcome from Edward. The nobles greet Gaveston with cold sarcasm, and he bridles at the insult, causing Lancaster and Mortimer to draw their swords and Gaveston to draw his. Mortimer wounds Gaveston, who is hustled off by an attendant. Edward banishes them from the court, and Warwick says, "Look to your own crown, if you back him thus." The king, the queen, and Kent exit, leaving the nobles to swear "To prosecute that Gaveston to the death" and to threaten to depose the king. A messenger brings word that Mortimer's uncle has been taken prisoner by the Scots, who are demanding five thousand pounds in ransom. Mortimer insists on going to the king for the ransom because his uncle has been taken prisoner in the king's war. Lancaster agrees to go with him, while the others go off to gather troops in their rebellion.
A guard prevents Mortimer and Lancaster from seeing the king, but Edward and Kent enter as they are arguing with the guard. When Mortimer tells the king the news, Edward declines to pay the ransom himself and tells Mortimer to pay it, giving him license to beg for the money "thoroughout the realm." Mortimer is insulted and touches the hilt of his sword threateningly while denouncing "The idle triumphs, masques, lascivious shows, / And prodigal gifts bestowed on Gaveston." Lancaster joins in denouncing the king's extravagance and his loss of prestige both at home and abroad, noting that the Scots have composed ballads mocking Edward. They depart, with Lancaster threatening, "Look next to see us with our ensigns spread."
Kent then angers the king further by warning him, "your love to Gaveston / Will be the ruin of the realm and you." Edward orders his brother "Out of my sight, and trouble me no more," and Kent leaves him. The queen enters with Gaveston and a retinue including the king's niece, Baldock and Spencer. Gaveston asks why the king doesn't send Mortimer to the tower, and Edward replies that "the people love him well." The niece introduces Edward to Baldock and Spencer, and Edward proclaims to her, "this day shall be your marriage feast. / And, Gaveston, think that I love thee well / To wed thee to our niece."
Kent joins the nobles in their revolt against the king, although he has to overcome their skepticism first. Lancaster announces that Gaveston and the king are there in Tynemouth, and that they are planning to attack and seize Gaveston, with the proviso, "None be so hardy as to touch the king, / But neither spare you Gaveston nor his friends."
Edward and Spencer enter, fleeing from the attack, followed by Gaveston, the queen and the king's niece. Edward sends Gaveston away by water while he and Spencer will travel by land. But when the queen asks Edward for a farewell, he denounces her as Mortimer's lover. The barons enter to find the queen lamenting her mistreatment. When Lancaster tells her "We would but rid the realm of Gaveston. / Tell us where he remains, and he shall die," she reveals, "He's gone by water unto Scarborough; / Pursue him quickly, and he cannot 'scape." She explains that the king and Gaveston separated to divide the forces of their attackers. And when the nobles leave, she admits that she is attracted to Mortimer, but will try to persuade the king to give up Gaveston. Otherwise, "My son and I will over into France, / And to the king my brother there complain / How Gaveston hath robbed me of his love."
Gaveston enters and is captured by the nobles. Lancaster likens him to -- who else? -- Helen of Troy, "the Greekish strumpet," because he has cause so many to take up arms. There is some dispute over whether they'll behead him or hang him, to which Gaveston responds, "Then I perceive / That heading is one, and hanging is the other, / And death is all." The Earl of Arundel enters, with a message from the king, who wants to see Gaveston before he dies. Warwick says, "we will gratify the king / In other matters; he must pardon us in this." Arundel insists, "he swears / He will but talk with him and send him back," and he offers to "be pledge for his return." Pembroke intervenes to say, "I will upon mine honour undertake / To carry him and bring him back again." They agree, reluctantly, and Gaveston says, "Sweet sovereign, yet I come / To see thee ere I die." But in an aside, Warwick says, "Yet not, perhaps, / If Warwick's wit and policy prevail."
Warwick prevails. He follows the men charged by Pembroke with looking after Gaveston and takes him.
Edward, Spencer and Baldock enter, and Spencer urges the king to behead the nobles who have taken Gaveston. Spencer's father arrives "with a band of bowmen and of pikes, / ... Sworn to defend King Edward's royal right." Edward creates Spencer Earl of Wiltshire, and announces that he intends to outbid the barons for the land Lord Bruce is selling. The queen enters with the news that her brother, the King of France, has seized Normandy, so he sends her and their son, the prince, to "parley with the King of France."
Arundel arrives with the news that Gaveston is dead by Warwick's hand. Edward kneels to vow:
Treacherous Warwick, traitorous Mortimer!
If I be England's king, in lakes of gore
Your headless trunks, your bodies will I trail,
That you may drink your fill and quaff in blood,
And stain my royal standard with the same,
That so my bloody colours may suggest
Remembrance of revenge....
He makes Spencer Earl of Gloucester and Lord Chamberlain. A herald arrives from "The barons up in arms" to say that they urge "That from your princely person you remove / This Spencer, as a putrefying branch / That deads the royal vine." Edward defiantly embraces Spencer.
The battle between the king's forces and the barons' take place.
The king's forces prevail and the barons and Kent are led in as captives. Kent is banished from court as punishment, but Warwick and Lancaster are led off by the elder Spencer to be beheaded, and Mortimer is sent to the Tower. When the king leaves, Spencer, a hanger-on named Levune, and Baldock remain to plot further. Spencer sends Levune to France to bribe "the lords of France" against the queen.