It's 1843, and Grace Marks has been convicted for her involvement in the vicious murders of her employer and his housekeeper and mistress. Some believe Grace is innocent; others think her evil or insane. Now serving a life sentence, Grace claims to have no memory of the murders.

An up-and-coming expert in the burgeoning field of mental illness is engaged by a group of reformers and spiritualists who seek a pardon for Grace. He listens to her story while bringing her closer and closer to the day she cannot remember. What will he find in attempting to unlock her memories?