The titular libertine is John Wilmot, 2nd Earl of Rochester (Depp), a notorious rake and poet in the court of King Charles II (Malkovich). He meets Elizabeth Barry (Morton), an actress whose budding talent blossoms and makes her much in demand under Rochester's tutelage. Wilmot and Barry become lovers. King Charles II, meanwhile, is torn between his great friendship with Wilmot and the danger posed by his displays of contempt for his monarchy. Pike plays Elizabeth Wilmot, Countess of Rochester; John's wife.
This film contains examples of:
- The Alcoholic: Rochester admits to be constantly under the influence of "the drink."
- Exact Words: Charles II, in need of money from France, asks Rochester to write a play in honour of the French Ambassador's visit, as a "testament" to his reign. Charles apparently forgets that Rochester, while a personal friend of his, has an utter contempt for the monarchy, so he writes Sodom, or the Quintessence of Debauchery, a scathing satire of the King's reign that involves live sex acts and vulgar imagery, claiming that it is, in Rochester's eyes, indeed "a testament to Charles" just what the King had asked for.
- I Warned You: When Rochester's friends introduce him to their new friend, 18-year-old Billy Downs, Rochester warns Downs, "Young man, you will die of this company." Later, when Downs is killed in a sword fight outside the home of a Constable, Rochester backs away from the dying man, whispering, "I told you."
- Love Martyr: It becomes clear that despite Rochester's health and infidelities, his wife Elizabeth continues to love him.
- Manly Tears: When Elizabeth dumps out Rochester's alcohol, he, sick and dying, dives for it, only to stop and realize that he's hit rock bottom. He bursts into sobs as Elizabeth holds him.
- Sex, Drugs and Rock & Roll: Rochester certainly enjoys the 17th century equivalent of it: Sex, drinking and writing bawdy plays.
- Teacher/Student Romance: Rochester and Barry become lovers after he takes her under his tutelage to coach her in acting.