The book tells the story of the early life of Henry Esmond, a colonel in the service of Queen Anne of England. Story opens on Henry as a boy – the supposedly illegitimate (and eventually orphaned) son of Thomas, the third Viscount Castlewood, and cousin of the Jacobite fourth viscount, Francis, and his wife, the Lady Castlewood. These successors to the Castlewood estate and peerage, following the death of Henry's father, foster the boy, and he remains with them throughout his youth and early adulthood.