The Conspirator, directed by Robert Redford, is a historical drama centered on a little-known aspect of the assassination of President Abraham Lincoln: the trial by military commission of Mary Surratt (Robin Wright), who ran the boarding house frequented by Lincoln’s assassin, the actor John Wilkes Booth. Surratt became the first woman to be executed by the US government (the next would be Ethel Rosenberg in 1953, a victim of Cold War anticommunist hysteria).

The film is an intelligent and well-acted telling of the events and generally stays close to the historical record. Screenwriter James Solomon spent some 14 years researching the story.

James McAvoy plays Union war hero Frederick Aiken, who defended Surratt at the request of her attorney, Maryland Senator Reverdy Johnson (Tom Wilkinson). Reverdy, a border state Southerner, was accused of disloyalty to the Union by members of the tribunal. Though he was able to avoid disqualification, he felt Surratt would be better served by having a Northerner of unimpeachable loyalty argue her case.