Taking up where Shakespeare’s Richard II leaves off, Henry IV Part 1, finds Bolingbroke, now King Henry IV, tenuously ruling England, as a man who usurped the throne and is not ordained of God. He is a ruler beset with troubles: civil strife in England, attacks by Scottish forces moving across the northern border, and the defeat and capture of his loyal Mortimer by the Scottish warrior, Glendower. Thus, he laments that he is unable to fulfill his earlier vow to lead a crusade to the Holy Land to do penance for his part in the death of Richard II. But there is one piece of good news: English forces, led by young Hotspur have defeated the Scots at Holmedon and have captured the renowned Earl of Douglas. Yet Hotspur’s show of valor especially gives the harassed king reason to lament the dereliction of his own son and heir, Prince Henry, a mirror image of Hotspur, who has avoided the court and public responsibility and spends his time in the company of the elderly, high-spirited Sir John Falstaff, as well as the lowly gang of hangers-on at the Boar’s Head Tavern in Eastcheap.
Prince Hal, as Prince Henry is appropriately called in this setting, joins with Poins, Bardolph, and Peto in a plan to gull Falstaff, contriving to have him participate in a robbery at Gadshill, be robbed in turn, and finally exposed as a coward and liar. Alone, Prince Hal soliloquizes, letting the audience know that, although he now chooses to enjoy himself in riotous company, he has no illusions about the character of his associates and will redeem himself publicly at the proper time.
Meanwhile, back at court, King Henry confronts the Percy family (Hotspur, his father Northumberland, and his uncle Worcester) over their not turning prisoners of war over to the crown. The Percys, deeply resenting the fact that the man they helped to the throne now intends to enforce absolute obedience, begin to plot their revolt. They will make peace with Glendower and gain his support and that of the captured Mortimer. Then, aided by Welsh and Scottish forces, the latter led by Douglas, they plan war against King Henry IV.
At the Boar’s Inn, the robbery and the duping of Falstaff is winding up riotously. However, as usual, Falstaff not only survives the ordeal of being derided as a coward and liar but emerges (as he usually does) triumphant. But the riotous fun is soon interrupted by a messenger from the king summoning Prince Hal to court to help counter the uprising of the Percys.
As the rebels are planning their campaign against the royal forces, King Henry rebukes his son for his wild ways, comparing him unfavorably to the valiant Hotspur. But when Hal pledges to redeem his tarnished reputation “on Percy’s head,” the king not only forgives him, but puts him in command of part of the royal forces, even allowing Falstaff to go to the wars in charge of a company of foot soldiers. At that very moment, the two learn that the rebels are preparing to assemble at Shrewsbury.
Prince Hal acts quickly now, seeking rectitude by reimbursing the travelers who were robbed at Gadshill, arranging for Falstaff’s commissioning as a leader of the king’s forces, and preparing seriously to go to war himself.
Partly because of new life breathed into the royal forces by Prince Hal’s sudden change of heart and spirit, the northern rebellion goes badly, Glendower and Northumberland desert the cause, and King Henry offers complete pardon to all if the rebels will disband. However, Worcester, the rebel messenger, does not tell the others about the king’s offer, convinced that under any circumstances the older leaders of the revolt will be the objects of Henry’s wrath.
In the hot engagement which follows, Prince Hal leads the successful battle and kills his spirited rival, Hotspur, even though Falstaff takes the credit. Worcester is captured and executed and the rebel forces are utterly defeated and scattered. King Henry IV follows up this victory by departing with Prince Hal toward Wales “to fight with Glendower and the Earl of March.”