Cynthia Daventry, the heroine of the story, grows up in Argentina as the adopted daughter of Robert and Jane Daventry, an English couple. Unable to have children themselves, they had adopted Cynthia at the age of three from a foundling hospital where she had been left by her dissolute father, James Glanville, following her mother's death in an earthquake. Cynthia is unaware of her parentage, and is horrified when on her 17th birthday her natural father arrives unannounced to claim her, intending to force her into prostitution in Buenos Aires and live off the proceeds. The Daventrys flee back to England, where they live comfortably although Cynthia never shakes off her deep-rooted fears.
After the Daventrys' death, Cynthia marries Captain Harry Rames, an up-and-coming politician whom she had first admired years earlier when as a naval officer he had led an expedition to the Antarctic. She realises that Rames does not love her but hopes that he will in time. Meanwhile, she throws herself into furthering his political career, while secretly regretting that his activities are driven not by any inner conviction but by his desire to win power and influence.
Some years later, in spite of Rames' increasing success he quite suddenly loses interest in politics, though he hides the fact from Cynthia whom he has now started to love. For her part, Cynthia recognises a change and suspects that he might have taken a lover. When Rames eventually admits that his long-sublimated passion for the Antarctic has reasserted itself, Cynthia consents to his abandoning politics and leading a new expedition south. During the three years that Rames is away Cynthia goes back to live in her childhood home in Argentina. Ultimately, Rames returns safely to her.