The themes of Mary Shelley's novels often parallel the path of her personal experience. She probes issues in her work that she explores in her life, asking whether total devotion to individual liberty and the unrelenting pursuit of knowledge through experimentation benefit either individuals or societies.

That she spends her life asking and acting out these questions is not surprising, for she is surrounded by radical free-thinking romantics all her life.

Her mother, Mary Wollstonecraft, is a pioneer feminist writer who dies shortly after Mary's birth. Mary reveres her mother's memory and frequently visits her mother's gravesite. But her father, William Godwin, makes an even deeper impression on Mary. Godwin, a tremendously influential political philosopher, an artist, and an anarchist, claims to have unshakable faith in the powers of reason to bring about ethical behavior.

As depicted in Leighton's book, Mary remains devoted to...