Vanity Fair opens as two young women leave Miss Pinkerton's school. Amelia Sedley is sweet, rich, and conventional; her friend Becky Sharp is clever, poor, and orphaned, with nothing to live on but her own gifts. Thackeray subtitles the book a novel without a hero, and from the start he treats it as a show he is staging, a fair full of cheating, jilting, and ambition that he watches with amused melancholy.
Becky's career is the engine of the book. Denied money and family, she sets out to win both. She nearly snares Amelia's foolish brother Jos, then takes a post as governess at Queen's Crawley, charms the whole disorderly household, and secretly marries the dashing, spendthrift Rawdon Crawley, losing them a rich aunt's fortune in the process. Becky's talent is reading what a room wants and supplying it, and for a long stretch the trick works.
Amelia's story runs alongside as a study in misplaced devotion. She marries the vain George Osborne against his father's wishes, just as the Napoleonic wars pull the men toward Belgium. At the battle of Waterloo George is killed, and Amelia spends the years after as a grieving widow, idolizing his memory and overlooking the patient, unglamorous Captain Dobbin, who has loved her steadily and quietly all along.
Becky and Rawdon meanwhile live brilliantly on debt and other people's money, and Becky rises toward the highest society under the patronage of the powerful Lord Steyne. The climb breaks when Rawdon, released from a debtors' sponging-house, returns home to find Steyne alone with his wife and her jewels. He strikes the lord, casts off Becky, and her glittering position collapses, though whether she was guilty or merely careless the narrator leaves deliberately unclear.
In the long close, Dobbin's constancy is finally rewarded when Amelia, nudged by a spiteful revelation from Becky herself, lets go of George's idealized memory and marries him, though Thackeray hints the prize cost more than it was worth. Becky drifts through European spa towns and reattaches herself to the ailing Jos, profiting from his death. The book ends on its refrain, Vanitas Vanitatum, asking which of us is happy in this world and shutting up the box of puppets.