Alias Grace tells the story of the murders of Thomas Kinnear and his housekeeper Nancy Montgomery in 1843 in Canada. The protagonist is Grace Marks, who along with James McDermott, was convicted of the crime and sentenced to life in prison. Based on a true story, the novel follows Grace and her interactions with fictional doctor Simon Jordan as he researches her case.
Grace has been hired out of prison to work as a servant in the home of the governor of the prison and a committee of Methodist churchgoers is working towards her pardon and release. The hope is that Jordan can prove she is simply hysterical rather than murderous. Though he is meant to be studying Grace as a criminal, Jordan gradually becomes more personally involved with Grace and her story as he struggles to understand how such a mild-mannered woman could have committed the crimes she was convicted of.
Grace tells Jordan her story in vivid detail, beginning with her early childhood in Ireland and her difficult family life. She goes on to describe her first job as a servant and how she came to work for Thomas Kinnear. She reveals the truth of Kinnear's affair with his housekeeper, and the events which led to their deaths. Throughout her story, Grace claims that she cannot remember the details of the murder itself.
Eventually, Dr. Jordan abandons the case, though he acknowledges that Grace may have a mental disorder which could explain everything. He joins the army, gets married, and Grace Marks is later pardoned. She goes on to change her name and get a fresh start in the United States.
