"Conviction" tells an amazing true story, spanning roughly thirty-five years over the course of a compact, economical 106 minutes. Weaving back and forth through the timeline, director Tony Goldwyn (2006's "The Last Kiss") and screenwriter Pamela Gray (1999's "A Walk on the Moon") ensure that the narrative avoids the choppy pitfalls of like-minded biographical films with a lot of ground to cover. Topped off by a superb cast of heavy hitters who have no trouble disappearing into their characters, the film enthralls and inspires without resorting to pandering tactics or cheap melodrama. The recently manipulative, threadbare "Secretariat," also based on real events, could have learned a thing or two from this superior effort. The only disappointment may be in viewers discovering after the fact that the film's postscript omits one glaring detail that would have turned a well-made but predictable movie into a rattling, devastating one encapsulating the bitter unforeseen curves life throws at us.

When her beloved older brother Kenny (Sam Rockwell) is convicted of first degree murder in the brutal 1980 slaying of neighborhood woman Katharina Brow, waitress and mother Betty Anne Waters (Hilary Swank) is sure that he didn't do it and vows to do whatever it takes to prove his innocence. Starting without even a high school diploma, Betty Anne earns her GED and against all odds works her way through law school. Her sacrifices are great—she loses an unsupportive husband (Loren Dean) and isn't able to spend as much time with sons Richard (Conor Donovan) and Ben (Owen Campbell), who ultimately decide to live with their father—and her chances of finding enough evidence to exonerate Kenny are slim. As the years tick by and hope dwindles for a frustrated, aging Kenny, the advent of DNA profiling and the discovery that several trial witnesses mysteriously perjured themselves on the stand suddenly give Betty Anne a newfound drive to finish the mission she started.

In all the years that Betty Anne Waters dedicates to freeing her brother, she never once asks him if he is guilty or not. While this might seem like an oversight in the screenplay—or, at the very least, in the actions of Betty Anne—it is signified that their relationship is so close and intertwined that she doesn't need to; she knows Kenny, and is absolutely certain he would not be capable of committing such an atrocious act on a virtual stranger. Working on two different levels—on one, as an investigative procedural from the point-of-view of a studying attorney, and two, as a human-interest drama about the lengths we will go to help those that we love the most—"Conviction" is taut and absorbing, intimate and touching. Without blatantly bolding and underlining the place and setting, director Tony Goldwyn effectively uses authentic accents and hairstyles, grittily natural locales, and realistic background shading to focus in on a specific New England milieu and socioeconomic class. The storytelling is fluid, too, only one jump ahead in time (in the second scene where Betty Anne visits Kenny in jail, his hair slicked back and with more pronounced crow's feet) coming off as jarring.

The path the story takes will surprise few—if Betty Anne had failed, there wouldn't be a movie, after all—but it's in the satisfaction of watching the protagonist make something of herself and triumph over everything from an unjust legal system to crooked cops where the film gets its spark. Hilary Swank deserves to earn yet another Oscar nomination for her exceptional turn as Betty Anne Waters, her resolute nature and stubborn determination only sometimes shielding her vulnerability when it comes to the odds she's up against and her feelings of failure when her teenage sons ask to live with their father instead of her. Also amazing is the way her mannerisms and body language so uncannily resemble Bailee Madison's (2009's "Brothers"), as the young Betty Anne. In nearly every scene, Swank becomes the character she is playing with the same seeming effortlessness that she brought to 1999's "Boys Don't Cry," 2004's "Million Dollar Baby," and 2009's "Amelia." Simply put, her range appears to be boundless; like Meryl Streep before her, there's no role she can't do.

As the imprisoned Kenny Waters, Sam Rockwell (2010's "Iron Man 2") never compromises a portrayal that is intentionally difficult to read at times. In flashbacks, Kenny is seen as a rough and tumble type, loving to his baby daughter but with a hot temper he doesn't always keep in check. Even as Betty Anne rues anyone who doubts Kenny's innocence, the viewer can't help but also question whether there's a chance he might be guilty. Beyond all that, the affection and care he shows for his sister is beautifully played, as is his frustration at rotting away in a jail cell for a crime he didn't commit. Lending fine support, Minnie Driver (2004's "The Phantom of the Opera") brings devotion and spunk to Abra Rice, a fellow law student who seeks Betty Anne out and demands they be friends ("We're the only ones in class who have been through puberty," she says), while Juliette Lewis (2010's "The Switch") is at her deliciously grimy best as Kenny's dead-toothed ex-girlfriend Roseanna Perry, whose slang and speech perfectly inform her character without turning her into a caricature ("I was railroad!" she exclaims at one point, meaning "railroaded"). Additionally worthy of special mention is Ari Graynor (2009's "Whip It"), a stirring, eye-grabbing standout as Kenny's grown daughter Mandy, who discovers that all she's been told about her father have been lies and fabrications. Graynor, usually used in comedic roles, is so wonderfully low-key and solemn here it doesn't even feel like the same actor.

"Conviction" is a highly competent, oftentimes quite impressive piece of work with one sizable debit: director Tony Goldwyn wrongfully opts to not be forthcoming to his audience in the end. A little research into the actual non-fictional happenings reveals that Kenny was, indeed, exonerated and set free, but that he tragically died six months later in a freak falling accident. It's a tough, bittersweet end that is never mentioned even in the concluding postscript, traded in for a comparatively happy-go-lucky finale that feels dishonest. Yes, the focal point is Betty Anne's dedicated fight for the love of her brother and her eventual triumph, but that doesn't take away the cruelly ironic circumstances of what happened next. Judged on its own merits, "Conviction" is a riveting entertainment, but it could have been something altogether deeper and more thought-provoking had the filmmakers played fair with audiences.