Like last year's Ray, this electrifying biopic of Johnny Cash reduces its complicated hero to a walking childhood trauma, attributing his 60s drug addiction to an older brother's accidental death in a circular-saw accident. But here the pop mythology takes a backseat to an old-fashioned showbiz romance that traces the married singer's 13-year infatuation with country singer June Carter. As the star-crossed couple, Joaquin Phoenix and Reese Witherspoon contribute all their own vocals, and their soapier scenes together reminded me of no less than the 1954 A Star Is Born. The story is framed by Cash's legendary 1968 performance at Folsom Prison, an appropriate metaphor for the singer's emotional incarceration and the love that sets him free. James Mangold (Cop Land) directed; with Ginnifer Goodwin and Robert Patrick. PG-13, 136 min. Century 12 and CineArts 6, Crown Village 18, Davis, Ford City, Gardens 7-13, Golf Glen, Lake, Lincoln Village, Norridge, River East 21, Village, Webster Place.