Following the assassination of President Abraham Lincoln, the mother of one of the suspects (Robin Wright) is charged with conspiracy to murder. James McAvoy is the Union soldier-turned-lawyer charged with her defence. Despite being pitted against his natural loyalties and confronting a military court unfairly weighed in favour of the prosecution, he pursues his case with an unexpected vigour, alienating his fiancée and the establishment. Strong performances distinguish this solid drama from director Robert Redford.
Despite the furore following the slaying of President Lincoln in a Washington theatre, the killers were quickly tracked down and apprehended.
All of them, except John Surratt (Scott Pilgrim's Johnny Simmons), the fresh-faced son of a Southern widow (Wright) who ran the boarding house where the conspirators plotted their outrage.
However, during the hysterical witchhunt - vociferously backed by hawkish war secretary Stanton (Kline) - she too is rounded up and finds herself shackled in a military prison alongside the assassins.
It looks like she's heading for the drop until Reverdy Johnson (Wilkinson), the doveish former attorney general who is concerned with law being upheld, persuades a reluctant Fredrick Aiken (McAvoy), a Union war hero, to take her case.
It's a familiar story of justice being denied but director Robert Redford propels the action along with a practised ease, helped by a solid showing from a bearded McAvoy as the honourable man doing the decent thing.
Colm Meaney delivers good villain as the inflexible army judge more concerned with a swift verdict than justice done while Kline veers towards the panto season with his Machiavellian patriot turn as what amounts to a Tea Party pin-up.
Wright lends Mary Surratt a quiet dignity and an intriguing emotional chasm opens as Aiken realises that her loyalty to her rebel son doesn't preclude going to the gallows to save his skin.
It's a robust, well-made movie that squares up to some of the more unpalatable truths and doesn't pull its punches when confronted with a difficult denouement.
It certainly questions the honesty of the hackneyed phrase "land of the free".