Johnny Cash has always been the man in black. His suit reflected his rebellious lyrics about doing hard time and waiting for the ultimate judgment at the end of it all. But outside the walls of Folsom Prison, not much was really known about the country legend.

Joaquin Phoenix takes us through the early years of Cash’s life – from the poor farming family he grew up in to the addictive powers of stardom – in the new biopic “Walk The Line.”

Phoenix’s voice reaches an octave lower as he and costar Reese Witherspoon sing their own way through Cash’s gospel upbringing and rise to folk/country immortality and his eventual downfall with prescription pain killers, infidelity and prison.

Far outweighing the majority of the rest of the film, Phoenix and Witherspoon’s immersion into their characters is impressive to say the least. In the four years it took to make this film, they were able to morph into the famous duo, and Phoenix’s sound was as gifted and spirited as many of Cash’s originals.

He is equally impressive as Cash during difficult periods of his life – dealing with divorce, alienation and drug withdrawal. These are genuine portrayals of a demigod fallen from grace in his performance.

Witherspoon’s supporting performance also reflects an intimate relationship between actor and character. Her learned Southern accent only scratches the surface of the subtle detail and mannerisms she picked up in her study of June Carter, Cash’s one, true love and reluctant wife.

Her voice lessons pay off as well in her attempts at Carter’s music. She sings with a flair that is rarely seen from someone who isn’t a veteran in the country/folk genre, and managed to pull it off very convincingly.

There are problems with the film, however. The most noticeable of these failures is found in the composition of the movie itself. Director James Mangold had a lot on his plate and just wasn’t able to piece the massive amount of poignancy in Cash’s life in a seamless manner.

The film suffers the most with an abrupt ending that reflects a sense of giving up on Mangold’s part. The rest of the movie is so powerful and intimate that audiences are built up to a life-altering resolution to the film that never comes.

Witherspoon also has some trouble picking up some of the emotion that certain scenes require, making her a well-studied Carter but lacking in some emotional investment in some areas of the film.

Phoenix’s pain ultimately drowns out much of the struggle Witherspoon goes through, making it quite easy to overlook the emotional turmoil Carter felt during Cash’s darker days.

The lasting impression the film gives helps soften the blow to smaller oversights, however. For two and a half hours, you are watching Cash relive the early years of his life, not Phoenix playing Cash. He actually becomes the man in black, the legend. And when the film ends, you will realize you have been given a much deeper look at the already fascinating man we can only call Cash.