Robert Redford's latest film, ''The Conspirator,'' explores a time in American history that most of us probably never knew about, or at least forgot: the 1865 trial of Mary Surratt, a boarding house owner whose son was suspected of helping John Wilkes Booth assassinate Abraham Lincoln.
It should be tense and thrilling, full of rich, powerful performances; instead, it'll make you feel like you should be taking notes in preparation for a high school exam. And like the last film Redford directed, the terrorism drama ''Lions for Lambs,'' it's painfully preachy and sanctimonious.
James McAvoy stars as Frederick Aiken, a 28-year-old Civil War hero for the Union who's now the lawyer assigned to defend Mary (Robin Wright), the lone woman charged in the case. Being young and idealistic - and functioning as the kind of character Redford himself would have played decades ago - Aiken says he doesn't know whether Mary is guilty of conspiracy, but he feels she deserves a fair trial.
The entire nation is against her - and against him, too, by association. But Kevin Kline, as the power-hungry Secretary of War Edwin Stanton, makes it clear that someone must pay for the president's death. It may as well be Mary Surratt.
Redford's film, based on a script by James D. Solomon, is stately and respectable to a fault: It's too safe. It feels the need to bang us over the head with how important it is. And Redford is trying way too hard to make these events from a century and a half ago seem like a relevant metaphor for where we are as a nation post-9/11.
Nobody ever evolves here; ''The Conspirator'' doesn't offer characters so much as human representations of principles. Aiken is always determined and high-minded (and Alexis Bledel as his girlfriend is always sweet and boring.) Mary remains the stoic martyr, proudly prepared to do whatever she must to protect her son, until the very end. Stanton is always unscrupulously conniving and out for blood.
* "The Conspirator" stars James McAvoy, Robin Wright, Kevin Kline, Tom Wilkinson and Alexis Bledel. Robert Redford directs. Rated PG-13 for some violent content, its running time is 2:02. It is opens Friday at Maui Mall Megaplex.
Even the film's aesthetic motif is static and suffocating. Redford (with the help of cinematographer Newton Thomas Sigel) shoots nearly all his interiors the same way: dark rooms pierced with shafts of misty, unforgiving sunlight. Whether they're meant to provide enlightenment or cast blame, they feel repetitive.
Sure, ''The Conspirator'' has an excellent, pedigreed supporting cast including Tom Wilkinson, Colm Meaney, Danny Huston and Stephen Root in one great scene. (Justin Long, meanwhile, shows up with the worst fake facial hair known to mankind as one of Aiken's fellow soldiers, and his presence feels awkward and way too contemporary.)
But then, Wilkinson, as Aiken's superior, is saddled with clunky lines like: ''It's time to heal the nation, not wage more war.''
Even an actor of his versatility and stature can't make that sound like anything but what it is: a lecture.