London, 1870. Young Fanny and Lucy are playing with a ball in the street when it falls into a cellar. Going to retrieve it, she discovers a wine-bar-cum-brothel called 'The Hopwood Shades' in the basement of the house owned by her father, William Hopwood. This discovery causes her parents to send her away to boarding school, shortly after she receives a mysterious birthday present from one Clive Seymore.
Ten years later, Fanny returns home, but the happy atmosphere is shattered by an incident in which Lord Manderstoke forces his way into the Hopwood Shades and, when evicted, starts a brawl that ends with Hopwood fatally falling under the wheels of a horse-drawn carriage. At the inquest, Manderstoke is exonerated, and the Hopwood Shades is closed.
Close to death, Mrs Hopwood sends Fanny to stay with the mysterious Clive Seymore, who turns out to be a Cabinet minister - and Fanny's real father. But since this revelation would lead to scandal, she has to take a lowly position as a maid. While working for Seymore, she meets his secretary Harry Somerford, and a mutual attraction develops, though he is under the impression that she is Seymour's mistress, an understandable mistake given that they seem rather closer than master and servant would normally be.
Seymore's wife Alicia is under the same impression, and decides to use this as leverage to secure a divorce from Seymore, as she is conducting a torrid affair with Lord Manderstoke. Under pressure, Seymore is forced to reveal his true relationship with Fanny, whereupon Alicia threatens to expose him for fathering an illegitimate child - a revelation that would end his political career. Caught in a vicious circle, Seymore kills himself and Fanny flees, taking a job in a rough working-class pub.
She is tracked down by Harry, and the two fall in love, despite the objections of Harry's female relatives, who believe that there is an insurmountable class division between the two and that she will damage his social standing. He is prepared to ignore all this for love of Fanny, but Fanny decides that his career is more important than her, and she flees again.
Teaming up with her childhood friend Lucy and visiting a deceptively upmarket but in reality somewhat insalubrious dance establishment, Fanny encounters Lord Manderstoke again, but she is rescued by Harry before things turn nasty. They realise that they were meant for each other.
Fanny and Harry go to Paris, where by chance they spot Lucy performing as a dancer. Visiting her backstage, they encounter Lord Manderstoke, who is Lucy's lover. After Harry dashes a glass of champagne in his face (twice, to get the message across) he is challenged to a duel.
Harry and Manderstoke duel with pistols at dawn. Manderstoke is killed, but Harry is seriously wounded. At Harry's bedside, Fanny confronts his sister, who eventually comes to realise that only his love for Fanny can give him the strength he needs to recover.
