You probably know Tom Hiddleston from his breakout role as Thor's devious brother Loki in Marvel's Avengers franchise. Or perhaps you caught him as F. Scott Fitzgerald in Woody Allen's Midnight in Paris, or as a tortured vampire opposite Tilda Swinton in Jim Jarmusch's Only Lovers Left Alive. Regardless, you've never seen the dapper Brit quite like this—a gaunt, yodeling Hank Williams in Marc Abraham's biopic I Saw the Light. Hiddleston spent nearly five weeks preparing for the role, moving into Nashville-based musician Rodney Crowell's house to learn how to play guitar and sing like Williams, trading his English accent for a Southern twang and dropping enough weight to pass for the chronically ill country star. Despite the film's less-than-stellar reviews, it's worth a watch for Hiddleston's mesmerizing performance alone. Below, BAZAAR talks to the actor about stepping into the shoes of an American icon and the physical and mental toll of the role.

Harper's BAZAAR: Hank Williams. Did you ever imagine playing him in your life? Was that ever an idea in your head before you were offered that? 

Tom Hiddleston: No, never. 

HB: When you get a script and you sit down with it, what immediately draws you to it?

TH: I think it's a gut feeling, and it's usually some sort of an implicit presentation of a psychological challenge—or a challenge of psychological interpretation. I read the script and I was fascinated by Hank as I read him. And what I saw is a tension between his external charisma, wit and mischief and his internal vulnerability and turbulence; I've said that about other characters but particularly with him. He clearly had such energy and charm, and as a performer that's what people connected to. He had such generosity of spirit–it really translated when he was on stage. People said he was electrifying on stage...I mean, real raw star quality. But clearly it came from a very troubled place.

HB: Right, he's a genius but he is tortured. And he's very much human. 

TH: Right, and people talk about that like it's a cliché, but he was really damaged. And I was interested in that tension and I wanted to explore it, in spite of my abject terror about having to do things I've never done, like sing and play and change the way I looked and change the way I sounded and that kind of thing. 

HB: Did you lose a lot of weight for the role? 

TH: I did, yeah. I tried to do it in a healthy way. I understood it was part of the obligation. He was very thin, and then towards the end he was very frail. He was only eating eggs and ketchup once every three days because he was on prescription drugs and he was drinking. That's one of those things that you can't really fake, but I was very careful because I didn't want the representation of Hank's ill health to actually be dangerous for me. The easiest way to lose weight is to do more exercise and eat a bit a less, so I just ran a lot. I was in Nashville and staying with Rodney Crowell, who was helping me with the music, and he lives in some very hilly Tennessean terrain. So if we weren't singing or playing, I was running. 

HB: Was it mentally difficult for you, playing such a tortured character? 

TH: I had to go to some pretty dark places, but that's because that's where he is. He was just incredibly sad and lonely and the more successful he became the more lonely he became. He used to say the sunset was the lonesomest time of the day, and that's the mark of a man who's not happy. 

HB: It's pretty evident that he has a very hard time connecting with people on a personal level. He was not capable of really making himself vulnerable. 

TH: I think he struggled with intimacy and that he probably kept people at arm's length. I watched a great documentary in which some of his old bandmates are interviewed and one said, [in Southern accent] "Hank would look at you with that black stare and a crooked smile as if to say, 'you know who I am, hoss? I'm the greatest singer in the world.' And if you didn't think it, he'd convince you of it." Somebody else said, "all his life, he wanted to get up on that stage and be somebody, and then he got up there and found out that there weren't nothin' there."

HB: And the movie isn't about fame, per se, but in a way, it is. 

TH: Part of it is. It's about show business and the tension between staying true to one's art in the face of expanding commercial prospects. Hank wrote songs from the bottom of his heart and they connected with people, and as soon as those songs became hits, people wanted more. He used to say, [in Southern accent] "they're slicin' me up and sellin' me like bologna," and he didn't like it. And he didn't like being pushed around, he didn't like being told where to stand, or what to do or what to say, and he felt like it diminished him. In that respect, he was very rebellious and he struggled with it. I think he was ill-equipped for it–his sudden fame exposed him to so much temptation. He was away from home and on the road, and he had terrible back problems; I think that's when he drank from the well, in a bad way. It all happened too fast, and he had no control.

HB: You spent five weeks in Nashville before shooting the movie. You moved into musician Rodney Crowell's house to learn how to play music and sing like Hank. Is this the most intense prep you've ever done for a role? 

TH: For War Horse I spent about six weeks training with horses before shooting the cavalry charge, because I simply didn't have those skills. They seem like they're very different skills, but actually, to learn how to ride a horse and to learn how to play a guitar and how to sing—there are no shortcuts. I always put a little work in, if I'm honest. To me, that's such an important part of the process because when you arrive on set to shoot, you have to be ready. You don't have time to waste. But it's the hardest I've ever worked. I think it felt like that because it was so foreign to me, it was so new. There seemed to be so many elements of it: to find his speaking voice and learn the songs, and then learn how to play the songs as he played them, and then change my baritone register to sound like a tenor. And after that, to think about his alcoholism and his marriage. Marc [Abraham] and Lizzie [Elizabeth Olsen] and I would sit and think about how we were gonna play that. We talked a lot about Who's Afraid of Virigina Woolf, that marriage between Richard Burton and Elizabeth Taylor. It seems like a strange reference, but how to express the passion and volatility of their relationship. There were a lot of things to get a handle on, but it was so fulfilling. I hadn't seen [the film] for a long time, but I watched it again this week [at the premiere]–that was a journey of a thousand miles. 

HB: I'm obviously not an actor, so I can't imagine what it's like to work on something, then see it a year down the road in a completely different format.

TH: It's always the strangest thing about acting. Making I Saw The Light took five months of my life, thinking about it every minute of every day, working on it every single day. Your audience watches it in two hours. So to see all of that work compressed into two hours is still—and I've been doing this for fifteen years—remarkable. 

HB: How did you end up living with Rodney Crowell? 

TH: I remember calling Marc and I said, "All right, if I were playing an Olympic sprinter in a film, I would find someone to tell me how many miles a day I needed to run, and he would put me on a regimen. So, what's my training? I need that guy for this, because this is hallowed ground. For this, G. Marq Roswell, our producer, suggested Rodney. Rodney is one of the most respected musicians in Nashville. He's interesting because he's so personally attached to Hank; he saw Hank play on his father's shoulders when he was two years old, and that's one of his earliest memories. So I was [in Toronto] shooting Crimson Peak, and Rodney happened to have a family wedding in New York and he came with Marc through Toronto and we spent Easter Saturday together—exactly two years ago almost. We met for breakfast, and we sat around for an hour, eating scrambled eggs, talking about it. And then Marc finally went to the bathroom and I turned to Rodney, "you have to tell me what to do, because I don't really know where to start." I played the guitar as an amateur, as a student. And he turned to me and said, "well, I don't know how well you play." By the time Marc came back, he was teaching me "Long Gone Lonesome Blues," which I think is Hank's most difficult yodel. We spent nine hours in that hotel room. We spent all day just playing and he taught me the basics of Hank's musical constructions. He showed me how some of his biggest hits start in a key of E and move up a 1-4-5 chord progression, and it was like he had given me the key to unlocking a mystery because I suddenly had the secret and it actually wasn't technically that difficult to play. So by the end of this Saturday, we'd gone through nine of Hank's biggest hits, and I felt like if I was climbing this mountain, I was already someway up it already. I was like, ok, I think I know how to climb this thing.

HB: How do you jump in and out of that accent so quickly? It's not a Daniel Day Lewis method acting sort of thing. 

TH: It was not easy, especially at the beginning. It doesn't help me to stay in character because as a collaborator, I need to engage someone like Marc in asking him what he wants. If we're talking about the scene or we're talking about the shot, I want to be able to discuss that as Tom. It might be myself, Marc and Lizzie saying, "so in this scene, is this a stress fracture or is this a break? Is this gonna heal? How hot does it get? Do you think they start yelling at each other or is the tension between them under the surface?" I want to have those conversations as myself as opposed to as Hank, because it's all about communication. But then there were some days, especially in the more intense, emotional scenes or some of the singing scenes, where I would sort of stay in it, because it was easier to [be Hank] than it was to break character. 

Julie Kosin is the senior culture editor of ELLE.com, where she oversees all things movies, TV, books, music, and art, from trawling Netflix for a worthy binge to endorsing your next book club pick. She's the former director of audience strategy and entertainment at HarpersBAZAAR.com. When not glued to her laptop, she can be found taking pictures of her dog or haunting used bookstores.