As a potential agent for change, the fact-based drama Sing Sing is a phenomenal achievement.

As a film, however, it’s merely fine.

Powered by strong performances and an inspiring story, Greg Kwedar’s second feature suffers from an over-reliance on handheld camerawork and favoring obviousness over subtlety in its big emotional moments.

Nevertheless, Colman Domingo seems like a lock for a Best Actor nomination with every major awards body. His portrayal of Divine G — a wrongly imprisoned man at the titular institution who’s become the MVP of its Rehabilitation Through the Arts theater group — ripples with genuine pain and frustration at his situation as well as an intense love for the creative escape that gives his life meaning.

Likely destined to complement Domingo throughout awards season in the Supporting Actor category is Clarence "Divine Eye" Maclin. Playing a version of himself, the prison yard bruiser begins to realize his potential once Divine G and Mike Mike (veteran theater actor Sean San José) invite him to join the RTA.

Other than Paul Raci (Sound of Metal) as RTA leader Brent Buell, the ensemble is rounded out by former program participants likewise taking on variations on their real-life personas. The balance of professional and non-professional actors elevates Sing Sing’s authenticity — and it helps that everyone gives solid performances.

Why their terrific actions aren’t depicted through matching confident filmmaking remains a mystery. Though Kwedar manages to craft a phenomenal shot of Divine G and Mike Mike in what looks like a shared room but is really just them talking through the walls of their tiny cells, most of his other choices feel haphazard and lazy.

The same goes for the script by Kwedar and Clint Bentley, which increasingly opts for telling over showing and wraps up far too cleanly for a fairly raw film that otherwise subverts cliché inspirational beats.

Still, the acting and overall story are strong enough to withstand these flaws, and footage of actual RTA productions adds another layer of appeal to an already fascinating project.

Grade: B. Rated R. Now playing at the Fine Arts Theatre and Grail Moviehouse.

(Photo: A24)