British actor Tom Hiddleston walks to the edge of his Hank Williams character in ‘I Saw the Light’

Finding that broken feeling took a while, but when it came, just before midnight on the Louisiana set of “I Saw the Light,” Tom Hiddleston’s voice crawled into Hank Williams’ words as the blues played out slow and mournful to the hushed tune of a single guitar.

Hiddleston’s rendition of “Your Cheatin’ Heart” comes toward the end of writer-director Marc Abraham’s biopic, which opens Friday. A troubled man and a music legend, Williams, who died at 29 in 1953 after recording 30 Top 10 country music hits, left an indelible mark on American culture. Hiddleston, a British actor best known for his villain Loki in Marvel movies, said he felt the sting of torment and the weight of legacy in each song.

“It’s the hardest thing I’ve ever done,” said Hiddleston, who had to reinvent his inner musical rhythms and raise the pitch of his baritone to embody Williams’ tenor. “The moment I signed on I understood my duty to him and his family. You’ve got no choice but to throw your whole soul at it.”

Hiddleston traveled to Nashville and was coached by Rodney Crowell, a Grammy-winning country musician who introduced the actor not only to Williams’ music but to the work of bluesmen such as Jimmy Reed and Howlin’ Wolf. The two worked on blues chord progressions and how to get Hiddleston, whose British training had made him metronomically precise, to give the music air by hanging back slightly off the beat.

“Rodney used to say, ‘We’re shaking the Englishman out of you,’” said Hiddleston, who recalled their collaboration the other day as a white patio curtain lifted in the breeze and the faint sound of traffic drifted in from the Hollywood Hills. “I couldn’t have made it without Rodney. I needed a guide through the woods.”

Williams’ up-tempo songs, like “Hey, Good Lookin’,” and “Honky Tonkin’,” vibrated with coy fun and desire. But it was sparse and poetic ballads that earned Williams, who suffered back pain and was addicted to alcohol and drugs, the nickname “Hillbilly Shakespeare.” His voice could sound as if it had been through a storm; a bit of hurt pressing against the dawn with Alabama-inflected syllables that could curl a note back into a phrase or vanish.

In the years before his death, Williams, a former shipyard worker, seemed a man recounting defeats and laying bare his demons in a potent and beguiling mix of masculinity, stoicism and vulnerability. That raw plaintiveness transcended country music and inspired singers and songwriters including Bob Dylan, Neil Young, Tony Bennett, Norah Jones and Bruce Springsteen, who once said he wanted to crack Williams’ musical code to understand its “beautiful simplicity and its darkness and depth.”

In the film, Hiddleston as Williams, well into a night of boozing, explains to a writer the mood he evokes in songs such as “I’m So Lonesome I Could Cry”: “Everybody has a little darkness in ‘em,” he says. “Now, they may not like it. Don’t wanna know about it. But it’s there. ... I’m talking about things like anger, misery, sorrow, shame, and they hear it. I show it to ‘em. And they don’t have to take it home.”

Much of Williams’ singularity and heartbreak resonated in his voice, which could shift from somber to what Crowell called a “post-vaudeville yodel” that tested singers who tried to emulate him.

“Credit has to go to Tom’s work ethic. He’s a dedicated artist,” Crowell said of the 35-year-old Hiddleston. “Hank Williams was a yodeler and a blues singer, which is basically from the knees down and the neck up. Tom had to get hold of the mechanics of projecting his voice as a yodeler does. He had to break out of the trained Shakespeare actor chest voice and into the yodel. It’s a very difficult thing to master.”

The yodel warbled through “Lovesick Blues,” a song Crowell said was “a job for anybody.” Hiddleston did 62 takes of it in one day, which the actor said “felt like swimming in the ocean through seaweed and finally I was in clear water.” But the melancholy in “Your Cheatin’ Heart” was tough to personify. Hiddleston lived with the song for months but the magic didn’t arrive until late on a cold Friday night in Shreveport, La., after a long week of shooting.

“My voice sounded good and technically it was pleasing, but Rodney said he couldn’t hear the pain in it,” Hiddleston said. “He kept re-stating that it needed to be more painful, more aching, more mournful, more yearning.”

While the crew was setting up the shot, Hiddleston walked into a backyard. “The challenge of it was very solitary,” he said, “and I just went back inside and did it.”

Hiddleston did two takes with Crowell playing guitar off camera. The scene captured a man’s pain over a love lost and was an eerie glimpse at a life in spiral. After the last note was struck, Hiddleston, slipping into a Southern accent, remembered Crowell saying: “That’s it right there. You ain’t going to do no more. I’m going back to my hotel.”

“Tom put his butt on the line,” said Crowell, adding that he wanted to do the song live on the set to distill its intimacy. When Williams recorded it in 1952 he was months away from death. “It was one of the most beautiful performances Williams ever did. We had to capture the poignancy of that moment.”

Williams was rough, brash and unadorned. His early death, like those of other musicians including Janis Joplin, Jimi Hendrix, Kurt Cobain and Amy Winehouse, left behind astonishing work and endless conjecture at what might have come with age. Williams wore his flaws in public, showing up drunk at performances and forcing the Grand Ole Opry, the pinnacle he aspired to for years, to drop him. He died of heart failure in the back seat of his Cadillac on his way to a New Year’s Day concert in Canton, Ohio.

“Hank was one of those people who lived without a safety net,” Hiddleston said. “They make compelling artists because they stand at the edge of a cliff and look down and are unafraid of the fall. That’s why they’re so captivating. But I do have that safety catch. The difference between me and him is I will step back.”

Twitter: @JeffreyLAT

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