In theaters

WALK THE LINE, directed by James Mangold, written by Mangold and Gill Dennis, 138 minutes, rated PG-13.

We’ve walked this line before.

Big movie, great cast, Oscar buzz, all riding the rails of a story based on a famous musician’s life. At the end of 2004, two artists received similar treatment – Ray Charles in the excellent biopic of his life, “Ray,” and Bobby Darin in the underwhelming “Beyond the Sea,” which didn’t exactly create a splish splash at the box office, regardless of Kevin Spacey’s efforts to the contrary.

“Walk the Line,” on the other hand, will generate such a splash, and it’s a wave that likely will extend into the heart of the pending awards season.

The film, which James Mangold (“Identity,” “Cop Land,” “Girl, Interrupted”) based on a screenplay he co-wrote with Gill Dennis, follows the defining years of Johnny Cash’s life.

Mangold takes us from Cash’s difficult childhood in Arkansas, in which a pivotal event changed him and his relationship with his family forever, to his rise to fame, his struggle with drug addiction (thanks to an introduction to Elvis), his marital problems with first wife, Vivian (Ginnifer Goodwin), the great love he felt for June Carter (Reese Witherspoon), and the defining moment in which the grayness of an otherwise muddled, self-destructive life lifted during his knockout 1968 show at Folsom State Prison.

There, in front of 2,000 cheering inmates, all of Cash’s frustrations and successes, his disappointments and dark humor, his rage, loneliness and failures – particularly his failures, which he wore like badges on his black sleeves – allowed him to connect with these men in a performance that arguably was the best of his career.

The thing is, as with so many biopics focused on musicians, Mangold’s movie is essentially a film about overcoming addiction in order to further one’s path to legend. That familiarity would have done the movie no favors had Mangold not had the strength of subtlety, which shows throughout, and especially the terrific performances from his cast, who transcend formula by allowing audiences to fully invest themselves in what matters – the budding, turbulent relationship between Cash (Joaquin Phoenix) and June.

Giving their best performances to date, Phoenix and Witherspoon each do their own singing here while possessing the sort of chemistry that sets their particular ring of fire alive.

What Mangold and his performers understand is that there are times in one’s life when the most difficult thing to do is to give yourself over to someone, to open your heart and trust that person, in spite of all signs suggesting that you’d be a fool to do so. This was the case for June Carter, who feared what marriage to Johnny Cash could mean, and Witherspoon gets it right, nailing the woman’s anxiety and apprehension. We all know the outcome, but it’s the building up to that moment that’s so compelling and, in the end, what “Walk the Line” really is all about.

Grade: A-

On video and DVD

MARCH OF THE PENGUINS, directed by Luc Jacquet, written by Jordan Roberts, 80 minutes, rated G.

It’s their bodies that you notice first.

Not made for flying, not particularly well made for walking, the emperor penguins of the Antarctic are awkwardly built, their rotund heft, stunted limbs and gnarled feet creating a curious waddle that’s at once comic and endearing. It’s only when they swim in the electric blue of this faraway deep that these beautiful creatures realize a ballet of physical release that seems beyond their capabilities.

Still, on land, where these penguins spend most of their lives, they are designed in ways that appear completely wrong for the process that takes up so much of their lives – breeding. Pegged to a life of almost impossible difficulty, these driven, nearly 4-foot-tall birds must walk more than 70 miles through the most treacherous terrain and weather in order to come to a place in which they feel safe to hatch their chicks.

And then, to find food, they must walk those 70 miles again. And again. And again. Meanwhile, starvation is a thief that has its way with them.

It’s this moving journey that is the focus of Luc Jacquet’s excellent, often harrowing documentary, a likely contender for Best Documentary when the Academy nominates this February.

Morgan Freeman narrates without a trace of emotion – respect is what he achieves. Following the penguins over the course of a year, director Jacquet chronicles a quest that finds the birds facing death daily in an effort to sustain life. Blizzards strike. Water is sparse, but for the resourceful bird, it can be found after the storms in pellets of snow. When the exhausted females leave for the ocean to find food, the males are left behind for two months to balance the egg on their hooked feet. There is no food for them, just patience, hardship, endurance. Should the egg touch the frozen surface, it will freeze in seconds and life will be lost.

And so they can’t drop it – though some accidentally do. It’s the wail of grief that rings from their throats that binds us to them – just as it does when the females return to either see their hatched chicks for the first time, or to realize that in their absence, their mate failed to keep the egg safe.

In the Antarctic, where the southern lights weave through the skies like hallucinogenic ribbons, the emperor penguins endure.

Grade: A

Visit www.weekinrewind.com, the archive of Bangor Daily News film critic Christopher Smith’s reviews, which appear Mondays in Discovering, Fridays in Happening, and Weekends in Television. He may be reached at Christopher@weekinrewind.com.