If you think the Johnny Cash presented in the Oscar-winning "Walk the Line" is an accurate portrayal of the late country legend, Jonathan Holiff wants you to think again.

“This is the anti-‘Walk the Line,’ the anti-Hollywood story,” Holiff told FOX411’s Pop Tarts column of his documentary “My Father and the Man in Black.” “This is never before seen or told information that will shock and surprise. This isn’t spoon fed by a studio or the Cash estate. Johnny was the original bad boy.”

Holiff is the son of Saul Holiff, the man who managed Cash’s life and career through the sixties and early seventies, introduced him to June Carter, and even handled his divorce from first wife Vivian. His film offers a unique glimpse into the working relationship of his cold, distant father and the troubled country music legend through recently discovered audio diaries and secretly recorded telephone calls.

Six months before the critically-acclaimed Cash biopic “Walk the Line” hit theaters in 2005, the elder Holiff – who parted ways with Cash in the mid-seventies and had been estranged from his son Jonathan for 20 years – committed suicide, leaving no note. However, the same month that the Joaquin Phoenix/Reese Witherspoon-starring movie was released, his son was presented a key to his father’s old storage locker, and an opportunity to piece together answers as to why he was never there for his own children, and why he had been mum about his crazy life with Cash.

“I was nine months old when I went on my first Johnny Cash tour, but during childhood, I only really saw my father when my mother pulled us out of school and we got on a plane and went to wherever they were,” Holiff said. “My father wasn’t exactly emotionally involved, he didn’t share his feelings about Johnny with the family. Back then, men were men and women were women, and his job was to be the bread winner and say ‘Honey, everything is okay.’”

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And while Holiff said he often resented Cash for “taking his father away,” at the same time, he adulated the larger-than-life character.

“I really though Johnny was a super hero – he was six foot two and dressed all in black. He was charismatic, and I was convinced that he would grow a cape and fly away... Johnny enjoyed needling my father, who was a pretty humorless person, and all about business,” Holiff reminisced. “He knew that my parents outlawed television and candy in our house, so when we saw Johnny in the green room, he would dump loads of candy in our palms. He enjoyed spoiling us because he knew my father didn’t allow it.”

“My Father and the Man in Black” offers an intimate portrayal of Cash’s personal problems through the height of his stardom – a time when Cash could sell out stadiums but was sometimes too drugged out to turn up. When Cash cleaned up and became born-again Christian in 1971, Holiff said his constant preaching to his father -- a Jewish/Atheist – brought about the end of their business and personal relationship.

“We were at the dinner table when I told my father and he absolutely hit the roof. He went crazy,” Holiff said, recalling the time he came from school crying after being teased over his three-syllable name and declared he was going to call himself “John” instead of “Jonathan.” “(My dad) told me that there was a Christian name, and I was not going to use it. I never understood why he was so hostile about it, but at the very time I was coming home saying that, there was another John in his life trying to convert him. Johnny was just a stage name, everyone around (Cash) then called him John.”

But as Holiff points out, Cash’s life story itself took on on almost religious proportions and ended up illustrating the powerful Christian theme of redemption.

“They were both human beings and are deeply flawed characters,” he said of his father and the singer. “Cash’s family may not endorse this film, but they probably aren’t going to stand in my way.”

“My Father the Man in Black” opens in select theaters September 6.