Antoinette's story is told from the time of her youth in Jamaica, to her unhappy marriage to an English gentleman, Mr. Rochester, who renames her Bertha, declares her mad, takes her to England, and isolates her from the rest of the world in his mansion.

Wide Sargasso Sea explores the power of relationships between men and women and discusses the themes of race, Caribbean history, and assimilation as Antoinette is caught in a white, patriarchal society in which she fully belongs neither to Europe nor to Jamaica.

Antoinette's widowed Martinique mother, Annette, must remarry to wealthy English gentleman Mr. Mason, who is hoping to exploit his new wife's situation.

Angry at the returning prosperity of the planter class, emancipated slaves living in Coulibri burn down Annette's house, killing Antoinette's mentally disabled younger brother, Pierre.

Part Two alternates between the points of view of Antoinette and her husband during their honeymoon excursion to her mother's summer estate Granbois, Dominica.

The story traces her relationship with Grace Poole, the servant who is tasked with guarding her, as well as her disintegrating life with Mr. Rochester, as he hides her from the world.

Expressing her thoughts in stream of consciousness, Antoinette dreams of flames engulfing the house and her freedom from the life she has there, and believes it is her destiny to fulfill the vision.

The villagers, inadvertently or not, kill Antoinette's brother, setting fire to the home and seem poised to murder the rest of the family if not for the apparition of an ill omen - their dying green parrot.

Scholar Lee Erwin describes this paradox through the scene in which Antoinette's childhood home Coulibri is burned down and she runs to Tia, a black girl her own age, to "be like her".

[6] In the novel, Rhys also explores the legacy of slavery and the slave trade, focusing on how abolition dramatically affected the status of Antoinette's family as planters in colonial Jamaica.

Scholar Trevor Hope has noted that the "triumphant conflagration of Thornfield Hall in Wide Sargasso Sea may at one level mark a vengeful attack upon the earlier textual structure".

Hope has suggested that the novel "[takes] residence inside the textual domicile of empire in order to bring about its disintegration or even, indeed, its conflagration".

The book was virtually completed in November 1964 when Rhys, who was 74 years old and complained of the cold and rain in her shack, suffered a heart attack.