In early 19th century England, while watching military exercises, George IV, Prince of Wales, is impressed by the swordsmanship of the dashing Capt. George Bryan Brummell. When the prince pays his compliments, Brummell responds with suggestions for improving the design of the regiment's uniforms, and George, who designed the uniforms himself, is offended. Brummell, a man of exacting sartorial and Epicurean tastes, is unfazed by the prince's disapproval, and makes an appearance that evening, wearing daring stove pipe pants, at a regimental dinner. There he meets the beautiful Lady Patricia Belham, the intended of George's political advisor, Lord Edwin Mercer. When Brummell refuses to retract his criticism of the uniforms, the prince discharges him from the service.Late that night, as Brummell watches his regiment embark on an overseas assignment, Patricia approaches him and asks why he is willing to sacrifice his military career. The proud Brummell explains that he is unwilling to compromise his dignity and self-respect, and impulsively kisses her. Brummell is left with no clear course for the future, however, as he has neither family name nor fortune. While strolling through town one day with his loyal valet Mortimer, Brummell sees politician Sir Ralph Sidley addressing a crowd. Brummell interrupts Sidley's speech with some sharply worded comments about the prince, and a newspaper reporter invites him to repeat his opinions the following evening at a civic meeting. Brummell accepts, and quickly makes a name for himself with his stinging indictment of the prince's excesses.Later, George is urged by Mercer and his prime minister, William Pitt, to end his relationship with his widowed, Catholic lover, Mrs. Maria Anne Fitzherbert, and make an advantageous marriage. Brummell is summoned by the prince, and as he urges George to stand up to Pitt, a bond begins to grow between the two men. One evening, when Brummell returns from the prince's birthday party, Mortimer warns him that his numerous creditors are growing impatient and suggests they go abroad. Brummell, who has become George's close friend and confidant, refuses, insisting that the prince needs him. Patricia drops by, and after Brummell shows her his exquisitely furnished house, they admit their strong feelings for each other. Patricia considers him too unstable to be a good candidate for marriage, however, and Brummell soon learns that her engagement to Mercer will be announced at an upcoming hunting party. Brummell is present at the gathering, and the prince publicly praises him for his devotion, promising to make Brummell an earl when he becomes king.While the other guests are fox hunting, Brummell and Patricia find themselves alone in the woods, and they fall into a passionate embrace. After the hunt, Mercer brusquely tells Patricia they should cancel their engagement, but she promises never to see Brummell again. The following morning, the distraught prince tells Brummell that Mrs. Fitzherbert is planning to leave for Italy. Brummell tells the prince that Pitt has been concealing the fact that King George III has gone mad. He urges the prince to have his father certified insane and declare himself regent, which would empower him to marry whomever he pleases.With Brummell and several doctors at his side, the prince goes to court and calls on George III, who is declared mad after he fails to recognize his son and tries to strangle him. Parliament limits the prince's power as acting regent, although it does grant him authority to change the marriage act, which forbids marriage to a Catholic, and make it possible for George to wed Mrs. Fitzherbert. Brummell advises the prince to reject Parliament's conditions, however, or lose power to Pitt. Emotionally overwrought, the prince turns on Brummell, accusing him of acting out of self-interest. Brummell insults the prince, and their close friendship ends. When his break with the prince becomes known, Brummell's creditors close in, and Brummell and Mortimer flee to Calais, France. Time passes, and the prince ascends to the throne after the death of George III in 1820.One day, George tells Mercer, who is now married to Patricia, that he has heard Brummell is sick and impoverished. George requests Mercer to discreetly provide assistance to his former friend. Meanwhile, in a freezing garret in Calais, the ailing Brummell declines a lucrative offer to publish his memoirs lest they prove embarrassing to the king. Brummell's health declines, and he is visited on his deathbed by George, who is in Calais on state business. Brummell is greatly moved by the king's visit, and the two men have an emotional reunion. After the king leaves, Brummell dies, his heart finally at peace.