In early 19th-century England, vibrant young Caroline Ponsonby accepts the marriage proposal of up-and-coming MP William Lamb, despite strong objections by William’s haughty mother, Lady Melbourne. Critical of Caroline’s mother for the indiscretions of her past amorous affairs, Lady Melbourne warns her son that the marriage will be unhappy and pities him when he admits that he is in love. William takes Caroline to Italy for their honeymoon and although Caroline’s high-spirited nature causes mild concern among the upper class social circles that they frequent, William is content. One evening in Rome, Caroline insists they stop at the darkened Coliseum in which she imagines the dramas of its ancient past. When the Lambs’ coachman, Antonio, warns them that several beggars have gathered outside the Coliseum, Caroline impulsively requests they be allowed inside. Although shocked by the tattered, dirty crowd that quickly gathers, Caroline is angered by what she considers William’s stingy offering of a few coins. Recklessly, Caroline hurls her diamond bracelet to the mob and is horrified when, moments later, she finds the ragged man who caught the jewelry beaten to death outside. Returning to London for the opening of Parliament, William resumes his seat and, upon making a strong argument against a Whig amendment, comes to the attention of Tory leader George Canning. One afternoon Caroline, escorted by young acquaintances Harry St. John and James Buckham, drive to a park where they watch a series of public boxing matches. Impressed by one handsome young man’s sly defeat of the prevailing winner, Caroline asks to meet him. Although the young man, Lord George Byron, is bitterly sensitive about his impoverished state, he nevertheless accepts Caroline’s invitation to dinner. Later, made curious by Byron’s resentful yet ambitious attitude, Caroline agrees to accompany him to his apartment where she discovers a series of poems he has written. Declaring that he has worked on his latest piece for more than two years with no guarantee of publication, Byron nevertheless proudly refuses Caroline’s offer to buy the poem. Soon after meeting Caroline, Byron’s first poem is printed and when it proves enormously popular with the public, the writer negotiates a beneficial contract with the publishing house. Invited soon after to a ball given by the socially prominent Lord and Lady Holland, Byron purposely makes a late entrance only to abandon the fawning crowd when he spots Caroline. Miffed when Caroline stalks away from him, Byron pursues her to a greenhouse where she accuses him of blatantly scandalous behavior. Admitting that she is frightened of the new freedom and authority he has acquired since his success, Caroline is nevertheless unable to resist Byron’s seduction, and the two become lovers. Upon returning home to William the next day, Caroline confesses that she has fallen in love with Byron. Dismissing her comparison of his poetry with the writings of the esteemed 18th century poet Alexander Pope, William asks Caroline if she can conduct the affair with discretion, but she insists true love can never be discrete. Over the next several weeks, Caroline makes her obsession with Byron increasingly obvious in public, which, when witnessed by Lady Melbourne, reaches William’s notice. Dispirited, William’s mood begins affecting his work in Parliament. Unwilling to curtail her public display of devotion to Byron, Caroline, dressed as a Nubian slave, heedlessly attends a costume ball with him and is stunned when the revelers treat her risqué attire with derision. Shocked when Byron asks for an introduction to the attractive young Miss Isabella Milbanke, Caroline makes a scene, but when Byron refuses to accede to her demand to leave, Caroline is forced to depart alone to the laughter of the guests. After Lady Melbourne relates the incident to William and remarks confidently that she is certain Byron will take up with Miss Milbanke, William defends his wife’s behavior as being prompted by her certainty that she is in love. Shortly after the costume ball, Byron enrages Caroline by informing her that he wishes to escort Miss Milbanke to a dinner at the home of the Duke of Wellington. Learning that the vainglorious Byron has arranged a fancy carriage with page escorts running alongside carrying torches to take him and Miss Milbanke to the dinner, Caroline disguises herself as one of the pages, convinced her impudence will amuse Byron and win back his affections. Upon arriving at Wellington’s stately home, however, Byron recognizes Caroline, and when she calls out her love for him, he dismisses her as ridiculous. Shattered by the rejection, Caroline forces her way into the dining room where in front of Byron she declares love is not ridiculous and slashes her wrists. Three months later, William and Canning have an audience with King George IV, who, sympathetic to the loss of William’s reputation at the hands of his wife, offers him the post of First Secretary to Ireland. After William reveals that Caroline has not spoken since her suicide attempt, the king admits that Lady Melbourne related her hope that her son would seek a divorce. Incensed to realize that his mother has arranged the new posting with the king, her former lover, William refuses the offer. Upon departing the court, Canning frankly advises William to choose between his career and Caroline. Returning home, William confronts his mute and haggard wife, declaring that he will not forgive her if she is feigning her illness. Sputtering that she has been too ashamed to speak, Caroline embraces William and the couple is reconciled. To Lady Melbourne’s dismay, William withdraws from Parliament and spends the next several weeks tending to Caroline, who gradually recovers from her emotional trauma. One day, while William is absent, Lady Melbourne confronts Caroline to accuse her of wrecking William’s career. When Caroline maintains that she has associates in high places, including the king, who will help William, Lady Melbourne reveals the Ireland posting was stipulated on William’s divorcing Caroline. Angrily recognizing Lady Melbourne’s influence with the king, Caroline impulsively leaves the estate for London, seeking the Duke of Wellington. Learning that the duke is in Paris, Caroline travels there and demands an audience. Although Wellington willingly entertains Caroline and takes her to bed, the next morning he states that he can do nothing for William and advises her to do the "fine" thing and leave her husband. Returning to the estate, Caroline summons solicitor Edwin Potter to request he draw up papers of separation. Requesting to meet Lady Melbourne privately, Caroline presents her with the papers, but when her mother-in-law attempts to thank her, she becomes hysterical. Weeks later, after the divorce is final, William sits in his lonely Irish lodgings with a large portrait of Caroline decorating his study. Still at Melbourne House, Caroline grows steadily despondent and one evening collapses during a rainstorm and dies. When Lady Melbourne asks the doctor for an explanation, he can provide none, but Caroline’s maid sadly avers that her mistress has died of a broken heart. Unimpressed, Lady Melbourne remarks, "My God, wouldn't she."