The story begins after President Lincoln was assassinated. Eight people were arrested for murdering the president. 42-year-old Mary (Robin Wright) is the only woman among them. Mary runs a family hotel, and the entire plan to assassinate the president was born in a room in this hotel. Aiken (James McAvoy) is a fledgling young and promising lawyer. He was ordered to defend Mary. Although Aiken knew that even with his defense, Mary would still be hard to escape the death penalty, he still decided to go through the process. However, after communicating with Mary, Aiken gradually began to doubt that Mary was really innocent. She was just a hostage who was threatened and used. No one believed Mary's innocence, and her life was completely in Aiken's hands.