Devotion in the highest degree...

Few modern actresses embody working-class pluck on screen as compellingly as Hilary Swank.

She collected her first Oscar in 2000 for her scintillating portrayal of murdered transgender teenager Brandon Teena in Boys Don’t Cry.

Five years later, Swank was back at the podium for her revelatory performance as a gutsy boxer in Clint Eastwood’s emotional Million Dollar Baby.

She famously celebrated that victory by tucking into a hamburger and fries at a fast food restaurant with her coveted golden statuette resting on the table next to the napkins and condiments.

Now, the Oscar-winning actress gets beneath the skin of another crusading real-life heroine in Conviction. Inspired by the story of a sister’s unwavering devotion to her jailbird brother, Tony Goldwyn’s film condenses an extraordinary 18-year quest for justice into a lean 107-minute courtroom thriller.

Betty Anne Waters (Swank) is a wife and mother of two in Massachusetts, who has always defended her troublemaker older brother, Kenny (Rockwell).

In 1980, Kenny is questioned about the murder of diner waitress Katharina Brow, but he is released to the annoyance of local cop Nancy Taylor (Leo). Two years later, ex-girlfriends Roseanna Perry (Lewis) and Brenda Marsh (DuVall) testify against Kenny and seal a murder conviction, resulting in a life sentence without parole.

Betty refuses to accept the verdict and she puts herself through college and law school in order to prove her brother’s innocence.

Her marriage implodes and she is left to raise their two sons, Richard (Donovan) and Ben (Campbell).

Aided by law school pal Abra Rice (Driver), Betty brings the case to the attention of attorney Barry Scheck (Gallagher) from the Innocence Project, an organisation that helps wrongly-convicted people overturn their sentences.

Conviction is a remarkable true story that provides Swank with a meaty central role that wrings tears and fury in equal measure.

The actress doesn’t strike a false emotional note and she gels convincingly with Rockwell as the hot-headed prisoner, who seems worryingly capable of the brutal crime.

Driver is a spunky sidekick, generating some much-needed flashes of comic relief amid all of the legal wrangling.

The screenplay stacks the odds heavily against Betty and Abra, so their valiant efforts leave us cheering in the aisles when it seems they might have finally discovered a fatal flaw in the prosecution’s case.

The seriousness of Kenny’s situation is brought home when one character coldly observes, “If Massachusetts had the death penalty, he’d be dead by now.”

On one point at least, the law worked in his favour.