Henry IV discusses with his lords the recent fighting against the Welsh and Scots, as a result of which Hotspur has refused to yield up his prisoners. Henry regrets that Prince Hal, his son, does not match Hotspur’s prowess. When Henry meets Hotspur, Northumberland, and Worcester, Hotspur still refuses to comply; all three later discuss their grievances and plan rebellion. Lady Percy tries and fails to find out from Hotspur what is happening. The rebels then meet with Mortimer and Glendower, and plan the division of England after their victory.
Meanwhile, Prince Hal is found at leisure with Falstaff and his companions. They plan a robbery for the next day at Gadshill, but Hal and Poins secretly plan to disguise themselves in buckram suits and rob the robbers of their gains. Events take place as predicted, and later in the tavern they play out the jest on Falstaff, who over-dramatises everything that happened. Hal and Falstaff then role-play the forthcoming meeting between Hal and the King, in which first Falstaff and then Hal take the part of the Henry. At the real meeting with the King, Hal resolves to reform, and plans for fighting the rebels are made. Falstaff and his companions also prepare to travel to the battle, and he begins to put together a fighting force which proves to be of abysmal quality.
Hotspur and his associates receive news from Northumberland that he is too sick to help them. They decide to proceed nonetheless. Blunt visits them with offers from the king, which they consider.
The Archbishop of York, a sympathizer of the rebels, reflects on the balance of power between the two sides. Worcester and Vernon visit the King, who extends them an offer of peace. Through them, Hal challenges Hotspur to single combat. However, Worcester hides these offers from the other rebels, and reports Henry’s defiance.
The battle of Shrewsbury begins. Several soldiers dressed in the likeness of Henry are killed by Douglas, including Blunt. Prince Hal and his brother Prince John both fight bravely, and Hal saves his father from being killed by Douglas. Hal then kills Hotspur. Falstaff, feigning death nearby, gets up when the fight is over and brings in Hotspur’s body, claiming to have killed him. With the battle won, Worcester and Vernon are sent for execution, but Douglas is released. Henry then makes plans for further attacks on the rebels in the north and west.