The lanky young evangelist from North Carolina was starting to attract media attention by the end of his 1949 tent revival in Los Angeles -- which means that professionals recorded his sermons.

So historians know exactly what the Rev. Billy Graham said during the sermons that changed Louis Zamperini's life. And because of author Laura Hillenbrand's 75-plus interviews with the Olympian and World War II bombardier, millions of readers know what happened inside his heart during the altar call.

In her 2010 bestseller "Unbroken," she wrote: "Why, Graham asked, is God silent when good men suffer? He began his answer by asking his audience to consider the evening sky. … 'I see the stars and can see the footprints of God. … I think to myself, my father, my heavenly father, hung them there with a flaming fingertip and holds them there with the power of his omnipotent hand … and he's not too busy running the whole universe to count the hairs on my head and see a sparrow when it falls, because God is interested in me.' "

Zamperini flashed back to his 47 days in a lifeboat after crashing in the Pacific, including the moment when he stared at the heavens and whispered: "If you will save me, I will serve you forever." Stunned, he tried to flee the tent, but Graham said: "You can leave while I'm preaching, but not now. … Every head bowed, every eye closed."

There's no way around the fact that this was the moment when Zamperini escaped his demons, said Matt Baer, producer of the 2014 movie "Unbroken" and of the new "Unbroken: Path to Redemption."

"At the end of the day, this is a true story," said Baer. Thus, they needed to show Graham in the pulpit and Zamperini on his knees, because "this was Lou's life. This was what happened. We had to show -- in a cinematic fashion -- that this is when his life changed."

This does, however, create a problem for a Hollywood moviemaker. The 2014 film directed by Angelina Jolie contained the camera-friendly scenes in which Zamperini competed in the Olympics, encountered Adolf Hitler, fought sharks in the Pacific and triumphed after brutal standoffs with prison-camp commander Mutsuhiro "The Bird" Watanabe.

The movie "Unbroken" ended with Zamperini coming home. That's where "Unbroken: Path to Redemption" begins, with a broken hero trying to wash away Post-Traumatic Stress Disorder nightmares with bottle after bottle of beer and whiskey.

This really happened: During one of many dreams in which he tried to kill Watanabe, Zamperini woke up because his wife was screaming -- he was actually strangling her.

Baer said it's hard to think of a conventional Hollywood film that told the whole story of a war survivor, including post-combat struggles with what counselors once dismissed as "war dreams." One classic that did -- "The Deer Hunter," in 1979 -- was three hours long. It would have taken that much screen time, or hours more in a miniseries, to do justice to the entire "Unbroken" story, he said.

In the end, said Baer, millions of people who read Hillenbrand's "Unbroken" know what happened after the war followed Zamperini home. They know about the love story that gave him hope and the terrors that nearly shattered his marriage. They know that this story included a revival tent, with the familiar image of Graham giving an altar call and a sinner being born again.

Zamperini went home that night and poured his whisky down the drain -- even the hidden bottles. He threw away his "girlie" magazines and dug out his air-corps Bible. He later traveled to Tokyo and, in a face-to-face meeting, forgave his prison guards.

Watanabe refused to face him. So Zamperini wrote his torturer a letter that ended with this: "I asked about you, and was told that you probably had committed Hara Kiri, which I was sad to hear. At that moment, like the others, I forgave you and now would hope that you would also become a Christian."

This isn't a normal movie plot. But it's what happened.

"My promise to Lou, 20 years ago, was that we would try to tell the whole story," said Baer. "This was the path that Lou walked and we wanted to put it on the screen."