The president was killed . . . and the truth was buried.
In the wake of Abraham Lincoln's assassination, seven men and one woman are arrested and charged with conspiring to kill the President and others. Against the ominous backdrop of post-Civil War Washington, war hero Frederick Aiken (James McAvoy) reluctantly agrees to defend the lone woman charged, Mary Surratt (Robin Wright), before a military tribunal. As the nation turns against her, Surratt is to rely on Aiken to uncover the truth and save her life.