For more than fifteen years, Irish-born Grace Marks has been confined for the 1843 murder of housekeeper, Nancy Montgomery, and her employer, Thomas Kinnear, at their home north of Toronto. Her convicted accomplice was hanged, accusing Grace with his last breath, but her sentence was commuted to life in prison at the last minute. Because of her amnesia and outbursts of rage and panic, she was held in the Lunatic Asylum before being sent to the Kingston [Ontario] Penitentiary.

Beautiful, intelligent, and strangely poised, Grace intrigues worthy townsfolk, spiritualists, and some of her jailers, who grant her the privilege of outside work, believe in her innocence, and strive for a pardon. In looking for medical approbation, they consult Dr. Simon Jordan, a young American doctor who is interested in insanity and memory loss. Without explaining his purpose, he brings her vegetables and other familiar objects, hoping to stimulate recollection of her life.

Interspersed with Jordan's own problems, Grace's story unfolds in her own words, from her poverty-stricken childhood in Ireland and the emigration voyage that killed her mother, leaving her and her younger siblings to a neglectful father, through her short life in service, to the dreadful events of autumn 1843. She has suffered many losses, including the death of her mother to ship fever, and that of her friend and fellow servant, Mary Whitney, from an illegally procured abortion. After many weeks, Jordan abandons his project in frustration and ambiguity. The novel ends years later with forty-six year-old Grace's discharge from prison in 1872, nearly thirty years after the crime.