In 1402 England, King Henry IV is forced to postpone his plans for crusades to the Holy Land in order to tend to unrest in England: Hotspur, Glendower, Mortimer, and Douglas have been fighting and the bloodthirsty warrior Hotspur refuses to turn over his war prisoners to the king, an ominous sign of disloyalty. Meanwhile, Prince Hal is drunkenly frolicking his youth away with Falstaff and Poins, even though King Henry wishes Hal could be the honorable soldier Hotspur is. In private, Hal reflects that his frivolous corruption is just an act and he will soon emerge into his true, honorable self, all the more impressive for being such a stark contrast. Hotspur argues at court with King Henry over the prisoners and over ransoming the captured Mortimer (whom the king insists is a good-for-nothing traitor). Hotspur emerges infuriated that his family is being disserved by the very man it helped raise to the throne back in the days of King Richard II. Behind Henry’s back, Worcester lets Hotspur and Northumberland in on a rebel plot he has strategized against the king. Hotspur eagerly embraces the plot and has no patience for Richard Scroop’s letters advising him to be cautious. He hurries to take action and bickers with Lady Percy on his way out.
As the rebels craft their plot, Prince Hal unfolds a plot of his own as he and Poins disguise themselves so that, after Falstaff, Bardolph, Gadshill, and Peto rob travelers carrying riches to the king, Hal and Poins can then easily rob their cowardly friends of the robbed loot. Later at the tavern, Prince Hal and Poins egg Falstaff on in outrageous lies about his bravery facing his robbers. When Hal reveals his ruse, he declares Falstaff’s cowardice exposed, but Falstaff insists he has been valiant as ever, he simply knew he shouldn’t wound a prince. Prince Hal receives a message from his father, summoning him to court and recounting the mounting treason plot. Hal and Falstaff take turns play-acting King Henry. When the sheriff arrives in search of Falstaff’s stolen loot, Hal covers for his friend.
In Wales, Hotspur, Mortimer, Glendower, and Worcester meet to pursue their plot and Hotspur argues heatedly with Glendower about celestial signs and with everyone about his prospective portion of the land they will win from the king. Lady Mortimer serenades her beloved husband in Welsh, a language he feels miserable not understanding. Hotspur bickers with Lady Percy. At London castle, Hal apologizes to King Henry for his irresponsible behavior and promises to redeem himself to honor in his father’s eyes. Back at the tavern, Falstaff insists to Hostess Quickly that he’s been pickpocketed, a claim she and Hal both call nonsense.
At Shrewsbury, Hotspur, Worcester, and Douglas prepare for battle and receive the bad news that Northumberland and Glendower won’t be able to join them. As an army captain (a position secured for him by Hal), Falstaff drafts cowardly men who pay him to fill their spots with pathetic lowlifes, leaving Falstaff rich and his troops helpless. Hotspur and the rest of the rebels sneer at King Henry’s efforts to negotiate peace. Back at York, Richard Scroop tries to drum up more allies for the rebels by writing to friends.
On the morning of the battle, King Henry attempts once more to negotiate peace but Worcester self-servingly misrepresents the king’s peace offering to the rebels as a battle cry (he fears a peace treaty will make him pay for Hotspur’s sins against the throne). The Battle of Shrewsbury commences and Douglas first slays the loyal Sir Walter Blunt, who is pretending to be King Henry to protect the king. Prince John surprises everyone by being an immensely brave soldier. Douglas fights King Henry himself, whose life is narrowly rescued by Prince Hal’s intervention. Hal then fights and kills Hotspur. Falstaff fakes his own death to escape being killed by Douglas, then claims to have killed Hotspur himself. King Henry’s side wins the battle. The king executes Worcester and Vernon while Hal spares Douglas’ life. The play ends with King Henry laying out his strategy for peace in England.