Matthew McConaughey as MUD (James Bridges/Roadside Attraction)

Ellis (Tye Sheridan) and Neckbone (Jacob Lofland, and yes, we won’t know him by any other name) are two adolescents living by the riverside in rural Arkansas. Neckbone has a discovery to show Ellis: a small boat has wound up many feet up in some trees on a very small island off of the river, possibly from a flood. When they go to see this boat, they discover someone is residing up there—a grizzled man with a cigarette in mouth who goes by the name Mud (Matthew McConaughey). He asks the kids if they can bring him some food —why not, Ellis says, he’s nice enough. Mud’s waiting for his love, Juniper (Reese Witherspoon), to come around so they can go off together.

Jeff Nichols’ follow up to his daring psychological drama Take Shelter (which also reunites him with collaborator Michael Shannon, though he’s in a minor role as Neckbone’s uncle), starts off like a kind of tall tale, but really this is a coming-of-age story mixed with a very dark romantic-dramatic thriller. While the plot has a pretty basic goal in mind—to get the boat out of the trees and get it running so Mud can leave—it’s much more of a character study of how Ellis sees Mud as a friend and more. Mud becomes a surrogate protector/father figure, even from afar, while to other people he may seem sinister.

And Ellis needs him. His parents (Ray McKinnon and Sarah Paulson) are planning on splitting up, causing his father’s seafood business to close. (In a simple but striking montage early on, Ellis rides in back of a pick-up truck going around making deliveries.) Ellis needs someone he can look out for, too. He’s a genuinely good kid, raised by parents who love him. But perhaps he’s almost too good in a way or just too trusting. After he punches out an abusive highs school boy picking on on a teenage girl, he gets a peck on the cheek from her. She’s his girlfriend now, right? Not really.

What drives Nichols’ film with such complexity is Ellis’s bond with Mud, and then by proxy Mud’s getting back together with Juniper. But should they? Very hard to say—maybe it’s more of a “they deserve each other” kind of thing. A mysterious townie played by Sam Shepard, who has known Mud since he was a kid, has seen how Mud, like Ellis, has read the wrong signs to become a do-gooder, in this case for Juniper, protecting her from abusive men. And the key reason—which is not too much a secret since Mud admits it with not too much shame as to why he’s hiding out—is that he has killed a man roughing her up, and the consequences of the death could put everyone in jeopardy. I mean, you don’t want Joe Don Baker on your ass.

I liked seeing Mud, Ellis, and Neckbone trying to figure out what to do with their lives in the moment, beat to beat. As in Take Shelter, the performances are stellar. Nichols never gets a moment that isn’t honest out of his ensemble. Perhaps in other hands this material could turn melodramatic, but I felt for Ellis every step of the way, and wanted to see Mud redeem himself in some manner, in large part because McConaughey is cool but tough. He still charms even (or despite) when he’s holding a gun. (McConaughey has had some deal with a devil somewhere to churn out such good work lately: Bernie, Magic Mike, Killer Joe.) And Sheridan is a real find, a natural actor with emotional openness, like Henry Thomas in E.T. the Extra Terrestrial. He portrays the angst of a young adult who can’t quite process the grief around him.

Mud may be slightly marred by being a little too long—not that I could adequately say what could be cut, though the very last scene spells out something that could have been left ambiguous—and a setup and payoff involving a snake felt a little obvious (though it also moves the story along a certain slightly conventional direction). But the writing, acting, direction, and this Southern environment with its rivers, dirt roads, dark motel rooms, and honky-tonk bars all build to something meaningful and genuine about good people, or people trying to be good in the face of hard obstacles. Nichols is a director who could become one of the best in American film in time, if not already.