The newly-created American Film Company, in the end credits of its very first feature, The Conspirator, announces its intentions to oversee the creation of "entertaining, engaging, and historically accurate" movies about great events in U.S. history, and this first effort comes so damn close. It is, as far as my limited expertise suggests, more than necessarily accurate; it is not quite so much entertaining and engaging. Though it's a hell of a lot more fun to watch than one might expect given the basic outline of the concept: director Robert Redford uses the trial of the Lincoln assassins as a metaphor for Gitmo.

In his eighth film as director, Redford does a much, much better job of presenting his liberal homily than in his last project, the unendurable thesis paper on celluloid Lions for Lambs. The Conspirator takes us back to the terrible days of mid-April, 1865, when the U.S. Civil War was a breath away from ending, and a resentful Southern sympathiser and actor named John Wilkes Booth (Toby Kebbell*) responded by assassinating president Abraham Lincoln during a production of the hit play Our American Cousin. So deep is Redford & Co.'s commitment to history that they force us to endure a good five minutes of what audiences in the middle of the 19th Century considered top-shelf farce, including the hi-fucking-larious line "You sockdologizing old mantrap", the very line that was Booth's cue to pull the trigger, knowing that the wave of boisterous laughter to follow would hide the sound of the gunshot - much as in The Man Who Knew Too Much, except it would be like if the London Symphony Orchestra had been playing "Chopsticks" instead of an Arthur Benjamin cantata.

In the aftermath of this crisis, Secretary of War Edwin Stanton (Kevin Kline) devotes all his energies to rounding up the clutch of conspirators responsible for the assassination and trying them as quickly as he possibly can in a military court, where he can be certain of receiving a "Guilty, now go hang the fuckers" verdict in record time. This sits poorly with Senator Reverdy Johnson (Tom Wilkinson), a firm believer in due process, habeas corpus, and the civilian trial of civilian criminals; thus, when Stanton's vendetta extends as far as Mary Surratt (Robin Wright), mother of known conspirator John Surratt (Johnny Simmons) and owner of the boarding house in Washington where the conspiracy was hatched, Reverdy can no longer sit back quietly, but orders his young protégé, Union war hero and attorney Frederick Aiken (James McAvoy), to defend Ms. Surratt in the face of seemingly intractable bias against her. Including Aiken's own feeling that she must be guilty, but as he sits in court and observes that the panel of generals, led by David Hunter (Colm Meaney), sitting in judgment of the accused has already made up their minds; that Stanton seems delighted to run roughshod over civil rights in favor of swift retribution and vengeance against a woman who may in fact be just as innocent as she proclaims.

Now, in the main, this is a fascinating story effectively unknown outside of Civil War aficionado circles, and it deserves the telling. Except for the declamatory parts, where a character (usually Reverdy or Stanton) stops the movie dead in its tracks to make some passionate speech that manages, just barely, to fit in character, but really is a sign of Redford and screenwriter James D. Solomon (working from a story he co-wrote with Gregory Bernstein) nudging us in the ribs a bit - "I say, don't you think Stanton sounds a little, I dunno, Rumsfeldey? OMG, and they both held the same cabinet position! I hadn't even noticed!" It's a queer thing: the film is never such a message picture that you get the feeling that The Conspirator is first and foremost a harangue about civil rights, but at the same time, those scenes are never far enough away that you can quite forget that they keep happening. It ends up feeling just a tiny bit desperate, the filmmakers's glancing at us nervously to make sure we Get It, and feeling just a little bit guilty that they stuck a PSA into their period courtroom drama in the first place. But not guilty enough to have not done it.

Indeed, the guiding principle behind the creation of The Conspirator appears to have been that under no circumstances should it be allowed to be completely enjoyable. As a legal thriller - and functionally, all the political asides and history lessons notwithstanding, that's structurally how the screenplay works - this could be a perfectly fun exercise, over-familiar genre tropes given a facelift by Mark Garner's absolutely gorgeous set design and Louise Frogley's costumes; disreputable or not, there's a certain delight in seeing pulp boilerplate working itself out in unfamiliar contexts. But the filmmakers are so concerned with the trappings that they struggle a bit with the story: The Conspirator is beholden to its production design, not enhanced by it, and the so very thoughtfully dusky and brownish cinematography by Newton Thomas Sigel manages to suck all the air out of the proceedings that Redford's characteristically over-precise direction, with its Very Suggestive camera angles and Refined Detachment from the material, hadn't already ground to dust (still, it's his most unfussy work since 1994's Quiz Show, still his single great moment as a director).

What that leaves is the characters and the actors, and generally they give more than the script gives them. In fact, there's not really a truly weak link in the whole cast: Kline gives his most restrained, straightforward performance in ages, and McAvoy is a terrifically inspired choice to play the muddled protagonist; the actor is not without his flaws, chiefly a sort of brittle desire that we feel sorry for him, and that fits this character better than most of the roles he plays. In small roles, Evan Rachel Wood and Justin Long both manage to avoid the traps of being smugly self-knowing that they sometimes fall into - something Wood spectacularly failed to do in the recent Mildred Pierce miniseries. The best in show, however, is unquestionably Wright; her role is barbarically trite - a woman who suffers, choosing to suffer even more to save her son - but the actress manages to salvage an incredible amount of humanity from the film's representation of her character as symbol and icon rather than person. She even manages to sell, barely, Redford's ham-handed use of Mary Surratt's widow's weeds as a visual signifier. And though the script often permits her to do nothing but stand quietly with thin-lipped determination, Wright even manages to make that credible, if not any more interesting than it has right to be.

The human element, plus the inherent fascination of the story, almost makes The Conspirator a good movie. Heck, it's at least watchable, in the "flipping by on cable, don't have the energy to keep looking" sense. It's stateliness and self-importance both ultimately make it feel like we're being talked at rather than invited to partake in a narrative process, but there have been, and will be, worse period pictures than this, and its worst sin is never incompetence, but only a certain airless lack of humor about what it's doing and how.