As the 15th century approached in England, Prince of Wales Henry V (Timothee Chalamet) indulged in a life filled with revelry alongside his close companion, John Falstaff (Joel Edgerton). This lifestyle drew the ire of his ailing father, King Henry IV (Ben Mendelsohn), whose health was rapidly deteriorating. In a desperate move, the king decreed that his younger son, Thomas (Dean-Charles Chapman), rather than Henry himself, would inherit the throne upon his death, much to Henry's dismay.
The unexpected uprising led by Percy (Tom Glynn-Carney) caught the court completely off guard. With Thomas still just a teenager and not ready for battle, Henry V passionately asked for the opportunity to confront Percy in a duel, aiming to minimize further conflict. Despite his initial hesitance, Thomas ultimately consented, and Henry V emerged triumphant, successfully quelling the rebellion but leaving his brother feeling eclipsed.
Tragedy struck when news of Thomas's sudden death reached King Henry IV, who then passed away, bequeathing the substantial burden of kingship to Henry V. At his coronation, gifts from far-off lands flooded in, including a controversial ball from France that would ignite tensions and set the stage for conflict.
Henry's sister, Phillipa (Thomasin McKenzie), warned him to be cautious of those around him, while William Gascoigne (Sean Harris), his trusted adviser, kept him informed of his brother's passing. The French gift was perceived as an insult, heightening the already growing whispers of impending war, a prospect that Henry V was reluctant to embrace.
Amidst the rising turmoil, William introduced Henry to a French assassin purportedly sent by King Louis himself to eliminate the English king. Meanwhile, a conspiratorial group comprising Cambridge (Edward Ashley) approached William, expressing their dissatisfaction with Henry's leadership. Their dissent was brutally silenced as Henry ordered their execution and declared war on France.
With diminishing faith in his advisors, Henry V turned to Falstaff, a seasoned veteran, to serve on his council. Together, they journeyed to France, capturing critical strongholds in the early skirmishes. A summit with the Dauphin (Robert Pattinson), Prince of France, deteriorated into a heated exchange of insults. In a horrifying act against British children, the Dauphin retaliated harshly.
Outraged, Henry contemplated a ruthless execution of all French captives, but Falstaff's wisdom urged him to practice restraint as tensions flared. As the British forces faced the formidable French army, Henry’s advisors recommended retreat in light of the daunting odds stacked against them. Yet, Falstaff remained steadfast, insisting they could triumph, citing an impending rainstorm that would impede the French army's charge.
Determined, Henry declared that should the skies open up, he would lead his men into battle. The skies obliged with a torrential downpour just as Falstaff, driven by his unwavering spirit, initiated the first assault.
Before the battle commenced, Henry met the Dauphin one last time, suggesting a duel to save their men from bloodshed. However, the French monarch demanded unconditional surrender instead. The clash erupted, with Henry delivering an impassioned speech that roused his troops. In the thick of battle, the Dauphin ultimately accepted Henry's duel, only to find himself bogged down in the mud, unable to move. Seizing the moment, Henry called on his men to act decisively.
After achieving victory, Henry faced a somber revelation: Falstaff lay dead on the battlefield. In the wake of their conflict, he met with the King of France to negotiate peace. As a token of goodwill, Henry was offered the hand of Catherine (Lily-Rose Depp), the king's daughter. However, their impending union was marred by Catherine’s probing questions regarding the violence that led them to this point.
Henry shared his belief that he had been driven to these actions by a supposed assassination plot originating from his father, a claim Catherine staunchly refuted. Upon confronting William, he unraveled the harsh truth: the supposed attempt on his life had been orchestrated to press him into action against France, ultimately consolidating his leadership of England.
In a fit of betrayal, Henry stabbed William, and upon returning to Catherine, he implored her to pledge one promise: always be honest with him, which she dutifully agreed to, solidifying their union with a vow of truthfulness.
