What if you were someone’s only hope? What if that someone was your brother? That’s exactly the scenario played out in “Conviction” and the position Betty Anne Waters (Hilary Swank) found herself in in 1983, when her brother, Kenny (Sam Rockwell), was convicted of murder. Wrongly, she believed. Based upon a true story, Betty Anne becomes a lawyer in order to exonerate her brother and works unceasingly for 18 years on his behalf. This fine little drama (could it be that dramas are returning to the Cineplex?) also stars the exquisite Melissa Leo as Kenny’s arresting officer. Minnie Driver is Betty Anne’s law school friend who gets involved, and Juliette Lewis does a truly patheticomic turn as one of Kenny’s old girlfriends. If the highest compliment you can give an actor is that their performance was a “revelation,” Lewis was a “revelation.” Betty Anne and Kenny basically grew up wild and running in the streets. They lived in foster homes and Kenny always found himself in trouble with the law. When he grew up, he was an easy person on whom to pin the gruesome murder of an elderly woman. The flashbacks of the pair as little playmate-hoodlums explain why they are “joined at the hip” in adulthood and are so fiercely devoted to each other. The filmmakers plant doubt in our minds about Kenny’s innocence, but Betty Anne never doubts her brother. Like Diane Lane in “The Perfect Storm,” and Uma Thurman in “Motherhood,” Swank is just a little too classically good-looking and refined in movement and demeanor to convince that she’s “average.” But her acting is truly in the moment and genuine. It’s difficult to say more about this film without giving away the ending. Was he innocent or not? Does he get out or not? You’ll have to see for yourself. In the vein of “Erin Brockovich,” “A Civil Action” and “The Hurricane,” the uniqueness of “Conviction” lies in its beautiful love story of a sister and brother, of the true meaning of family and of laying down one’s life for another.