In a world where everyone is striving for what is not worth having, no-one is more determined to climb to the heights of English Society than Becky Sharp. The lowly teaching assistant Becky issues her headmistress, Miss Pinkerton with an ultimatum - pay her properly to teach at the Academy for Young Ladies or find her a situation elsewhere. But Miss Pinkerton calls Becky's bluff, deciding to send her off into exile as a country governess. Kindly stockbroker's daughter Amelia Sedley takes pity on the poor homeless orphan and offers to take her home. Amelia’s dreams are like any other girl’s - she wants to be married and happy. But Becky wants to make sure tomorrow is better than today, and she seizes this opportunity to better herself.

In darkest Hampshire, Becky spends her days as governess to Sir Pitt Crawley’s neglected daughters. Her employer's handsome youngest son, Rawdon, does his best to interest Becky in a flirtation. But Becky's ambition is to get into her employer's good books, and soon she is promoted to the position of Sir Pitt's indispensable secretary. In London, Amelia's childhood sweetheart, George Osborne, never replies to any of her letters. George's father now opposes their marriage because he suspects the Sedley family business is failing. When Mr. Osborne calls in his loans, Amelia's father is ruined. Sir Pitt’s snobbish sister, Matilda, pays a visit to Queen's Crawley. Everyone is on their very best behavior, because they all yearn to be remembered in the rich old lady's will. Becky forms a new plan, and quickly charms her way to becoming Matilda’s favorite new companion. Matilda sweeps Becky off in her carriage, to Sir Pitt’s dismay. With a last secret smile for Captain Rawdon, Becky departs for London Town.

Becky has settled into life as Matilda Crawley’s favourite companion. But at Queen’s Crawley, Sir Pitt cannot cope without her. When Lady Crawley tumbles down the stairs to her death, Sir Pitt heads straight to London to see Becky. He wants her back - as his wife. Becky refuses, with the shocking news that she is secretly married already. Becky hatches a plan. She writes a letter to Matilda, laying bare the news to her beloved benefactress that the mystery husband is none other than the lady's favourite nephew, Rawdon. Matilda is horrified and cuts them both off. The Sedleys' bankruptcy leaves them no choice but to sell their house and all its contents. At the auction, Becky attempts to buy Amelia’s piano, but she is outbid by Dobbin. Mr Sedley is furious with Mr Osborne, and orders Amelia to call off her engagement with George, severing all ties between the families. With Napoleon on the loose, the young officers receive their marching orders for war. And Amelia and George finally take a stand for love over duty, and marry against their parents' wishes.

When George refuses to apologise for his marriage to Amelia, his father sends him a letter, cutting him off from the family and denying him his inheritance. All the friends set sail for Belgium, where Becky makes use of every opportunity to advance in society, laying on the charm with the great and the good. Even George is captivated by Becky’s new glamour, as Amelia notices with mounting dread. The cream of society attends a grand ball, where George hands Becky a letter declaring his feelings for her. Dobbin tries to comfort Amelia, but the band stops playing as General Tufto announces that Napoleon is marching on Brussels.

As the battle begins, Amelia is sick with the fear about George’s safety. But Jos is far more worried about himself, and Becky sees him as an opportunity to make some quick money. She sells him the horses Rawdon left behind for a ridiculously high price, and Jos scarpers. The Battle of Waterloo rages on, and the English battalion take up their firing positions. As they advance, one of their number is shot in the heart.

Becky and Rawdon are months behind on their rent payments, but Becky is far more interested in unashamedly flirting with Lord Steyne and extracting as much money as possible from him. With the Sedley family finances in tatters, Amelia makes the heart-breaking decision to let Georgy live with the Osbornes. Lord Steyne propels Becky to the very top of society. First, she and Rawdon are presented to the King. Next, Becky is invited to dinner at Lord Steyne’s house – one of the greatest houses in London. This is the moment she has always longed for. But Rawdon is accosted by bailiffs, and Steyne seizes the chance to see Becky alone.