Grace Marks was a poor, young Irish immigrant and domestic servant in Upper Canada and, along with a stable hand, was convicted of the brutal murders of their employer and his housekeeper in 1843. Grace was sentenced to life imprisonment, and became one of the most enigmatic and notorious women of 1840s Canada for her supposed role in the sensational double murder. Eventually exonerated after 30 years in jail, her conviction was controversial and sparked much debate about whether she was involved in the murder, or was merely an unwitting accessory.

In 1859, Simon dissects the events of the murders, while in 1842 Grace befriends Mary Whitney, whose death from a back-alley abortion traumatizes Grace to the point of hysteria.

In 1859 Simon attempts to extract Grace’s repressed memories of the murders. In 1842 Grace begins work as a servant at the Kinnear farmhouse.

In 1859 Simon becomes intimate with Mrs. Humphrey, while in 1843 Jamie confesses his love for Grace.

In 1859 Grace is convinced to try neuro-hypnosis to recover memories.

In 1859, Simon joins the Union Army, while in 1872 Grace gets unexpected news and makes a decision about her future.