Ellis and his friend Neckbone (really) are two Arkansas kids, living near (or, in Ellis's case, on) the river. Life is far from perfect: Neckbone lives with his goofy Uncle Galen, while Ellis's parents are on the verge of splitsville. Their families make their living from the river, and nobody's getting rich doing so.
But that doesn't mean kids can't do kid things. Specifically, they've found an abandoned boat storm-stranded high in the trees on a Mississippi River island. Cool! But their explorations uncover a guy (Matthew McConaughey) living on the island, dirty and uncivilized. His name: Mud. Mud provides them more adventure than bargained for.
Mud's goal is to run off with the once-lovely Juniper (Reese Witherspoon). Complicating things is that Mud is a fugitive wanted for killing Juniper's abusive boyfriend, so he's hiding both from the law and the boyfriend's rich and lawless family.
After two movies that were totally predictable, it was fun to see something different, with complex and sympathetic characters. There's an unexpectedly violent climax.
Michael Shannon plays goofy Uncle Galen, but does not once demand to be Kneeled Before.