Henry, also known as Hal and played by Timothée Chalamet, is the emotionally detached eldest son of King Henry IV (Ben Mendelsohn) of England. Disinterested in both his father's militaristic ambitions and the prospect of inheriting the throne, Hal's days are consumed by debauchery—drinking, wenching, and joking with his friend, John Falstaff (Joel Edgerton), in Eastcheap. When summoned by his father, Hal learns that his younger brother, Thomas (Dean-Charles Chapman), has been chosen to succeed the throne. Thomas is tasked with quelling the Hotspur rebellion, a disgruntled faction angry over their ongoing loyalty to the crown amidst no peace resolution in sight.
However, Hal's arrival shifts the tides as he challenges Hotspur ([Tom Glynn-Carney]) to a duel. What begins as a sword fight descends into an intense fistfight, ultimately leading to Hal killing Hotspur with a dagger. Though Hal's victory snatches glory from Thomas, who later dies in a separate battle in Wales, Hal's father's health wanes, and as Henry IV passes away, Hal ascends as King Henry V. Determined to forge a different path than his father's, Hal opts for diplomacy with his father's enemies, a decision perceived by many as a sign of weakness.
During his coronation feast, he receives a peculiar gift from the Dauphin of France (Robert Pattinson), who sends him a ball—a move meant to belittle him. Instead, Hal views this with nostalgia for his childhood. His sister, Philippa ([Thomasin McKenzie]), now Queen of Denmark, warns him that nobles are often self-serving and rarely express their true opinions.
As the plot thickens, Hal interrogates a captured assassin, who claims to have been dispatched by King Charles VI of France. Meanwhile, English nobles Cambridge ([Edward Ashley]) and Grey ([Stephen Fewell]) weigh their loyalties amidst shifting tides as they consult William Gascoigne ([Sean Harris]), Hal's Chief Justice, regarding their concerns over Hal's rule. Gascoigne advises Hal to project strength, leading him to declare war on France and execute Cambridge and Grey as traitors. Hal, placing his utmost trust in Falstaff, enlists him as his military commander.
As the English army embarks on its journey to France, Hal leads the charge, with Falstaff at his side. After a successful capture of Harfleur, they find themselves faced with a significant French force. Dorset (whose linkage is not specified) urges retreat, yet Falstaff devises a cunning strategy to lure the French into a compromising ambush. Hal offers to combat the Dauphin directly, but the challenge is brushed aside.
What follows is the famous Battle of Agincourt, where Hal fights valiantly. As Falstaff's tactics pay off, the outnumbered English emerge victorious, albeit at the cost of Falstaff's life on the battlefield. The Dauphin, humiliated in combat, faces further dire consequences when Hal orders the execution of French prisoners, a stark contrast to Falstaff's previous reluctance to carry out such orders.
Following their triumph, the English forces push further into France, resulting in Hal meeting King Charles VI, who concedes defeat and offers the hand of his daughter, Catherine (Lily-Rose Melody Depp). Upon returning to England with his new bride, Hal confronts Catherine in her chamber, where she challenges his decisions regarding the war. As they engage in a meaningful discussion, Hal realizes that the provocations against him for going to war were orchestrated by Gascoigne rather than stemming from true French aggression. In a moment of cold fury, Hal confronts Gascoigne, confirming his suspicions before ending Gascoigne's life. Returning to Catherine, he vows always to value and seek the truth in their relationship.
