The Gardener’s Wife begins where the romance of The Serpentine Garden Path leaves off.
After their marriage, Susan is shunned by her family and her husband John Dean is blacklisted. Unable to find work on an estate, he toils at Vauxhall Gardens, a well-known pleasure garden in London. They have four children in the space of five years.
After five years of struggle, John finds work on an estate in Scotland. At Ellon Castle, John is shocked to discover that his employer is not the Earl of Aberdeen, but rather the Earl’s mistress.
In this tiny and isolated village, Susan becomes friends with the mistress, an Englishwoman named Penelope Dering, against her husband’s wishes.
Both Susan and Penelope give birth to daughters within a few months of each other, which brings them even closer together.
Susan overhears John talking about emigration with the other servants and informs him that she is opposed to the plan. When Penelope also hears the news, she begs him to reconsider for the sake of his wife’s happiness. He is angry that she is privy to this private information. When Susan finds him in the garden burning refuse, he confronts her with the threat of eternal damnation if she does not end her friendship with Penelope. His graphic threat convinces her that he is serious and she decides to break it off with Penelope.
Penelope sends her son to the local school. There the Deans boys get into a fight trying to defend him against the bullying of the other children.
That night Penelope's son awakens the house with his cries as a result of a nightmare. John goes to Penelope’s apartment to reassure her son.
The next morning, when Penelope comes to thank the Dean boys, Susan espies John and Penelope whispering together and realizes that they must leave Ellon in order to save their marriage.