"Walk the Line," based upon two autobiographies by the late Johnny Cash, is the third high-profile music biopic in just over a year, and the best of the lot. That may be faint praise, since none of them (the other two were 2004's Ray Charles drama, "Ray," and 2004's Bobby Darin flick, "Beyond the Sea") have exactly stood out from the crowd in regard to storytelling innovation, but director James Mangold (2003's "Identity") works through this hurdle by centering the film around the love story between Cash and peppy fellow singer/tour buddy June Carter (Reese Witherspoon). This main plotline drives the film forward, gives heart to the meant-to-be lovebirds, and brings focus to the usual biopics that are all over the place, sketchily developed and predictable.

As with "Ray," "Walk the Line" touches on a whole lot of familiar territory; these films might be based on real lives, but those said lives are cliches when placed in a cinematic format. One can make a checklist as they go of the formulaic elements on display: the nervous audition where the artist performs for a record producer and gets signed; the sudden rise to fame and fortune; the strain that the musician's career has on his marriage; the gal on the side who might be better for him than his current wife; the drug addiction that threatens to ruin his career and the relationships he holds dearest, and finally, the tragic event from his childhood that, in part, shapes his own future and the person he becomes. "Walk the Line" has all of these things, walking its own fine line between old-hat and acceptably conventional, but the powerhouse performances from Joaquin Phoenix (2004's "Ladder 49") and Reese Witherspoon (2005's "Just Like Heaven") sell even the mustier of moments. These two have a hot and playful chemistry with each other, selling the notion along that way that Johnny Cash and June Carter were unequivocal soul mates.

The 1940s prologue set around the Arkansas cotton farm where Johnny was raised starts things on a high note, depicting a close, loving bond between his 12-year-old self (Ridge Canipe) and slightly older brother Jack (Lucas Till) before a freak accident while sawing wood takes Jack's life. Their hard-nosed father, Ray (Robert Patrick), doesn't even try to hide his resentment, proclaiming that God took the wrong son. This traumatic part of Johnny's childhood haunts him into adulthood (now played by Joaquin Phoenix), as he briefly goes into the military, takes a wife, Vivian (Ginnifer Goodwin), has children, and then manages to sign with a local record label. While on tour, he meets the effervescent June Carter (Reese Witherspoon), a smart firecracker of a country star who confesses that she makes up for her only fair singing voice by being an ace entertainer. Johnny, who has been a fan of June's for years, is instantly smitten and can't help it, eventually taking her on tour with him as his stardom rises. Myriad conflicts, however, get in the way of them becoming a couple: marriage, divorce, children, and Johnny's self-destructive addiction to pills.

As anyone with a passing knowledge of these iconic celebrities will already know from the start of "Walk the Line," Johnny Cash and June Carter Cash were happily married for thirty-five years, frequently collaborating with each other on artistic ventures and deeply in love until June's passing in 2003. Johnny died just a few months later, some attesting it to a broken heart. Because the viewer already knows where the film is going, climaxing in the late '60s with June's onstage acceptance of Johnny's marriage proposal, it is in the journey to that point that matters most. "Walk the Line" might have done a more thorough job of portraying the details of Johnny's early career and songwriting, and the overall narrative is told in a straightforward, unoriginal manner. Nonetheless, the fiery, complex relationship that forms between Johnny and June is an involving one, and writer-director James Mangold and co-screenwriter Gill Dennis stay away from the overdone melodramatics of "Ray."

If Joaquin Phoenix doesn't share an uncanny physical resemblance to Cash the way that Jamie Foxx managed as Ray Charles, he makes up for it by digging underneath this legend and evoking him through mannerism and voice. As strong as Foxx was in "Ray," the jury is still out if he did much more than do a great impersonation of him. Phoenix goes deeper than that, bringing stark but accessible emotions and an unashamed passion for June that makes him a likable presence throughout. He also amazes in his performance sequences—some of the most electrifying in the film, despite not personally being familiar with any of these earlier songs except "Ring of Fire"—capturing Cash's deep, one-of-a-kind voice and the cool command he had over concert audiences.

In a stunning turn of her own—maybe her best since 1999's "Election"—Reese Witherspoon plays June Carter with depth, warmth and insight, ably shedding her frothy romantic-comedy persona of the last few years and disappearing into the demanding part. Witherspoon turns out to be a talented singer herself, but where she genuinely impresses is in the way she effortlessly modulates her bubbly on-stage personality and her more serious, introspective side in her personal life. Witherspoon's June is a woman torn between responsibility and giving into her feelings; indeed, she resists Johnny's advances for so long not because she doesn't love him—it's obvious she does—but out of fear that he'll disappoint her and turn back to drugs.

Supporting performances are mostly peripherally written, with cameos from Elvis Presley (Tyler Hilton), Jerry Lee Lewis (Waylon Malloy Payne), Roy Orbison (Johnathan Rice), and Waylon Jennings (real-life son Shooter Jennings). As Johnny's first wife, Vivian, Ginnifer Goodwin (2003's "Win a Date with Tad Hamilton!") does a nice job of being harpy on occasion, but just as often sympathetic as she grows understandably suspect of what her husband does when he is away from her and on the road. Finally, Robert Patrick (2003's "Charlie's Angels: Full Throttle") superbly plays Johnny's father, Ray, as spiteful in his treatment of his son, who can never do enough to please him, but never as a one-dimensional caricature; their rocky relationship is plausible and painful to watch for all the right reasons.

"Walk the Line" is two-and-one-quarter hours in length, but only scrapes the surface of Johnny's life as a whole. By only covering a twenty-year span and ending in 1968, the movie deprives the viewer of some of Cash's greatest songs and his other work later in life. Even with the lessened time frame, the film, as with most biopics, moves a little unevenly through the years, passing them by with barely a scene or two each. If "Walk the Line" fails to break new ground or blow the viewer away, the central love story between these two famed public figures feels authentic and truthful, aided in no small part by Oscar-bound stars Joaquin Phoenix and Reese Witherspoon. By the end, there is no question that June made Johnny a better man, both personally and professionally. This is the main conceit in "Walk the Line," and one that director James Mangold illustrates just right.