A good indicator of James McAvoy's current status is his casting as the lead in the latest film by Hollywood veteran Robert Redford.

It’s not the size of the film that matters – his recent blockbuster X-Men: First Class will attract far more bums on seats. It’s that McAvoy’s role in The Conspirator is the kind of part – the idealist taking on the system – that any number of American icons from James Stewart to Tom Cruise have also played. This feels like an anointing.

The film is set in the immediate aftermath of the American Civil War and its shocking postscript, the assassination of Abraham Lincoln. As the country mourns its president, war secretary Edwin Stanton (Kevin Kline) believes that speedy retribution – in the guise of justice – will maintain the shaky peace.

The assassin, John Wilkes Booth, died while being captured; Stanton elects a military tribunal, rather than a civilian court, to ensure that the co-conspirators go to the gallows.

But one of them is a 42-year-old woman who protests her innocence. Mary Surratt (Robin Wright) owned the boarding house in which Booth and his friends hatched their plans; guilt by association is her fate. McAvoy plays Frederick Aitken, a Union war hero turned lawyer who, despite his own belief in Surratt’s guilt and the ignominy of defending a national pariah, agrees to represent her. He soon realises the conspiracy to kill the president is being answered by a conspiracy to pervert the course of justice.

Quiz Show aside, Redford has never been an interesting director, his nose for a good story not matched by flair. Here he takes some fascinating material and almost squeezes the life out of it. There’s not enough detail to make the period live, or drama in courtroom scenes that, by their nature, require an added zip and artistry.

That said, the story and actors keep us on board. It’s not hard to see echoes of the 1860s in America’s deliberate confusion of retribution for justice post 9/11, and Kline does very good work as the gruffly powerful Stanton, whose conviction that the end justifies the means is frightening. Opposite him, McAvoy is authentic, subtle, conveying a sense of honour without histrionics that many other actors would find instructive.

Larry Crowne is Tom Hanks’s second film as writer/director, a surprising 15 years after his well-regarded comedy-drama That Thing You Do! Like the actor himself, it is professional, unpretentious and likeable. But I can’t help feeling that with its timely scenario, and an on-form Julia Roberts starring beside him, it should have been significantly better.

The story concerns the efforts of middle-aged Crowne (Hanks) to pick himself up after he loses his job in a warehouse store, in the midst of the recession. Having had no formal education, he goes to college for the first time, where he meets bitter, jaded teacher Mercedes (Roberts).

Hanks and Roberts last starred together at the other end of the food chain – as a senator and a socialite in Charlie Wilson’s War – exchanging intelligent repartee as though they’d been flirting for years. Their rapport here is less fun and less convincing. But individually they convey well their characters’ inner lives – one in fear of penury, the other made miserable by a boorish husband and the dashing of her educational ideals.

If Hanks had stuck to his guns behind the camera, this could have achieved a delicate balance between comedy and pathos, carrying the chill of the economic crisis. Instead, he lets it descend into jolly, jangly feelgood.