The story is framed by its preface and coda as a puppet show taking place at a fair; the cover illustration of the serial instalments was not of the characters but of a troupe of comic actors at Speakers' Corner in Hyde Park. The narrator, variously a show manager or writer, appears at times within the work itself and is highly unreliable, repeating a tale of gossip at second or third hand.

Rebecca Sharp ("Becky") is a strong-willed, cunning, moneyless, young woman determined to make her way in society. After leaving school, Becky stays with Amelia Sedley ("Emmy"), who is a good-natured, simple-minded, young girl, of a wealthy London family. There, Becky meets the dashing and self-obsessed Captain George Osborne (Amelia's betrothed) and Amelia's brother Joseph ("Jos") Sedley, a clumsy and vainglorious but rich civil servant home from the East India Company. Hoping to marry Sedley, the richest young man she has met, Becky entices him, but she fails. George Osborne's friend Captain William Dobbin loves Amelia, but only wishes her happiness, which is centred on George.