Henry Esmond grows up at Castlewood. He knows there is some mystery about his birth, and he dimly remembers that long ago he lived with weavers who spoke a foreign tongue. Thomas Esmond, Viscount Castlewood, brought him to England and turned him over to Father Holt, the chaplain, to be educated. That much he learns as he grows older.
All is not peace and quiet at Castlewood in those years; Thomas Esmond and Father Holt were involved in a plot for the restoration of the exiled Stuart king, James II. When James attempts to recover Ireland for the Stuarts, Thomas Esmond rides off to his death at the Battle of the Boyne. His widow flees to her dower house at Chelsea. Father Holt disappears. Henry, a large-eyed, grave-faced twelve-year-old boy, is left alone with servants in the gloomy old house.
There his new guardians and distant cousins, Francis and Rachel Esmond, find him when they arrive to take possession of Castlewood. The new Viscount Castlewood, a bluff, loud-voiced man, greets the boy kindly enough. His wife is like a girl herself—she is only eight years older than Henry—and Henry thinks her the loveliest lady he has ever seen. With them are a little daughter, Beatrix, and a baby in arms, Frank.
As Henry grows older, he becomes increasingly concerned over the rift he sees developing between Rachel and her husband, both of whom he loves because they treat him as one of the immediate family. It is plain that the hard-drinking, hard-gambling nobleman is wearying of his quiet country life. After Rachel’s face is disfigured by smallpox, her altered appearance leads her husband to neglect her even more. Young Beatrix also feels that relations between her parents are strained.
When Henry is old enough, he is sent to Cambridge on money left to Rachel by a deceased relative. Later, when he returns to Castlewood on a vacation, he realizes for the first time that Beatrix is extremely pretty. Rachel has great regard for her young kinsman. Before his return from Cambridge, Rachel, according to Beatrix, goes to Henry’s room ten times to see that it is ready.
Relations between Rachel and the Viscount are all but severed when the notorious Lord Mohun visits Castlewood. Rachel knows her husband had been losing heavily to Mohun at cards, but when she speaks to the Viscount about the bad company he keeps, he flies into a rage. He is by no means calmed when Beatrix innocently blurts out to her father, in the company of Mohun, that the gentleman is interested in Rachel. Jealous of another man’s attentions to the wife he himself neglects, the Viscount determines to seek satisfaction in a duel.
The two men fight in London, where the Viscount had gone on the pretext of seeing a doctor. Henry suspects the real reason for the trip and goes along, for he hopes to engage Mohun in a duel himself and thus save the life of his beloved guardian. The Viscount, however, is in no mood to be cheated out of a quarrel. He is heavily in debt to Mohun and thinks a fight is the only honorable way out of his difficulties. Moreover, he knows Mohun wrote letters to Rachel, although, as the villain explains, she never answered them. They fight, and Mohun fatally wounds the Viscount. On his deathbed, the Viscount confesses to Henry that he is not an illegitimate child but the son of Thomas, Lord Castlewood, by an early marriage...