Lowly teaching assistant Becky issues headmistress Miss Pinkerton with an ultimatum – pay her properly to teach at her Academy for Young Ladies or find her a station elsewhere. Miss Pinkerton calls Becky's bluff, and Becky is forced to pack away her meagre possessions. Kindly stockbroker's daughter Amelia Sedley takes pity on the poor orphan and offers to take her home for the week.

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.

Becky lives with rich Aunt Matilda, and her future is looking bright. But as war clouds gather, everyone's fortunes take a tumble.

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.

The Napoleonic Wars enter their decisive moment as the battle of Waterloo gets underway, with George fighting on the front line. Becky has come to the conclusion that war is not such a bad thing, since it presents plenty of opportunities for money to be made.

Becky works out how to live well on nothing a year, but flies too high as she joins the dizzy ranks of lords, ladies and kings.

Becky is left alone in the world and living in greatly reduced circumstances when Steyne arranges for Rawdon to be shipped overseas. Dobbin discovers that Amelia plans to remarry, a revelation that inspires him to finally confess his feelings for her - but he is not prepared for her reaction. The Sedley family takes a holiday in Germany, where they are unexpectedly reunited with Becky - who gets the chance to perform a single good deed. Last in the series.