PARK CITY - In Jeff Nichols' "Mud," Matthew McConaughey tackles a truly charismatic spirit. A man of virtues, many of them at odds with themselves, the eponymous misfit is running from a dark, complex past and toward a brighter, idealized future in the film. He is a cauldron of opportunity for any actor, and McConaughey says that was very much what endeared him to Nichols' script in the first place.

In fact, Nichols had begun the project years ago in film school and had the actor in mind since day one. McConaughey smiles with pearly whites when asked about that fact. "I remember having a moment of going, 'Oh, I've been doing this acting thing for a while,'" the actor says, "'long enough where someone could have me in mind for an original script and write something. I like that.' And it was a side of me that I haven't ever really played. The guy's an adolescent. It's the dreamer side. I think we've all got it in us."

Indeed, Mud was a character harkening back to a certain time, "back to before you know better, and the lengths a man will go for love," McConaughey says. "If Mud ever came down to Earth and got pragmatic and said, 'Why am I chasing this girl,' if he ever had that sit-down, I think he'd die. It would be the end of him."

For some context, and at the risk of spoiling the story's measured, storybook unfolding, Mud is a character chasing his first love, Juniper (Reese Witherspoon), in the film. He's on the run after defending her honor in a deadly fashion, yet it's not so simple as that. Mud and Juniper have a long and complicated history, and anyone who has ever drifted apart and found his or her way back to a lover will get the dynamic immediately. That romance is at the heart of the story's themes, as Mud serves as a conduit for young Ellis (Tye Sheridan) in the film, a boy coming of age in a deteriorating family environment, desperate for truth in the fairytale ideal Mud preaches.

"Mud lives up in the clouds," McConaughey says. "He lives on that dream. He lives in that romanticism. He's an aristocrat of the heart, a prince of the heart…Ellis is getting bashed in the head with the reality about love. And here's this guy he runs into who is a living example, and a spoken example, saying, 'No, don't give up on the dream, man. Don't take the Kool-aid and get logical and realistic about this. Don't get pragmatic, man. Don't go above the shoulders on this thing. Don't try and make sense of it. It's love, man. Stick with your heart on it. And Mud's a beautiful, but some could argue sad, case, that he's going to do this the rest of his life."

On the contradictory nature of the character, Mud is marked by disgrace and nobility in the film, wisdom and lies. Regarding the latter, McConaughey notes that maybe there often isn't much of a demarkation between the two. "With Mud," he says, "if it ain't true, it ought to be. Is he full of shit? Sure, maybe. I don't know. Who's to say? But another thing about him that I kind of tapped into is this guy has stepped in shit so often and for so long he's come to see it as a God damn good luck charm. He's come to see it as like, 'Well, it must be a sign.' He's getting screwed over so often, he's chosen to go, 'That's a good luck thing.' And again, there's the dreamer. Kids do that after a while, too. His logic is astral."

The piece reminded McConaughey of certain films from the 1980s with its deliberate pacing, he says, and its tendency to allow the audience time to breathe with it. The imagery, the sound, the pacing and the words are all part and parcel of the poetry of it, he says. But he also went back to that period in his mind because that was when he was Ellis. He remembers having his heart in his throat asking a girl named Gretchen to go out with him once upon a time.

"That was the big thing then, to ask someone to 'go with you,'" he says. "And I remember someone going, 'You can write a note.' And I was like, 'No. After school I'm going to go to her in front of the buses and I'm going to ask her eye to eye. That's going to be so hard but I've got to feel that.' I went and did it and she said yes, thankfully.

"There's also the magical realism, which you wrote, and that's a very good two-word synopsis to let someone know what this has a lot of. Not as extreme as, say, 'Beasts of the Southern Wild,' but, you know, boat in a tree. Practically, yeah, that could happen. Hadn't seen it, but yeah, that could happen. And, 'I want to get this boat in the water.' Uh, okay. I guess that could happen. I'd like to see how this goes down. There's just such an innocence to the whole thing. Jeff wrote a beautiful script and I think he made a great movie."

Nichols had pursued McConaughey for the role at a busy time. The actor's agent passed the script along, particularly noting the writer/director's strong Southern voice, and McConaughey was keen to do it. "I talked to Jeff and I wasn't able to find a spot where I could release my work and really dive into the script," he recalls. "I said, 'Jeff, man, I'll get on it. Please don't haul ass with it. Stay on me. I'm gonna read this thing. I just need to finish up a bunch of work.'"

On the set, McConaughey says Nichols was "confident in that he could trust what he had on the page and he trusted what we got in the shot. He didn't over-complicate things. He didn't try to make a straight line crooked. Sometimes when it's working, directors and people in general can try to make it complicated. It was working and he let it evolve and let it roll out. And again, he wrote such a good script that we weren't going off page trying to make scenes into something they weren't. He knew what he wrote and why he wrote what he wrote."

And as for his young co-star, McConaughey says he treats Sheridan as a peer. "In a lot of ways, he's an intuitive old man," he says. "But when he acts, he doesn't have any attitude, yet he's old enough to know what having an attitude is. He's got a lot of poise and a lot of patience for a young man his age. And the other thing is he's not on screen acting older than his age. You can see him process things in a more mature way than a lot of kids his age do, but, again, he's not playing an attitude. And you see a lot of younger actors do that sometimes. He's wonderful."

From here McConaughey is off to New Orleans to begin work on the new HBO series "True Detective" with his friend Woody Harrelson. But for a blip here at the 35th annual Sundance Film Festival, he's a wonderful steward for a film looking for its second wind after launching at the Cannes Film Festival eight months ago.

"Mud" opens nationwide on April 26.