Starring Shia LaBeouf. Rated PG

Near the beginning of The Peanut Butter Falcon, a generally amiable tale of runaways and redemption, one traveller says of another, "Maybe he's living the American dream, like in a Mark Twain story."

That character won't be otherwise remembered for his book smarts, nor will the movie, which aspires to a kind of rolling-down-the-river Americana and gets maybe halfway there. More Shania than Mark, the Twain-ish fellow in question, played by Shia LaBeouf, is a bearded screwup who gets by in the swamps of North Carolina on charm and ingenuity. He's named Tyler, like codirector Tyler Nilson, who also wrote this debut feature with filmmaking partner Michael Schwartz.

When screen Tyler's feud with local crab fishermen (led by John Hawkes) heats up, he revs up his rusty bayou boat without realizing he has a stowaway: half-naked Zak (first-timer Zack Gottsagen), a Down-syndrome youngster who has just fled a haphazard community home where he shared a room with ever-crotchety Bruce Dern.

Initially nonplussed, Tyler is intrigued by Zak's persistence and agrees to help him find a pro-wrestling camp run by a TV personality called the Salt Water Redneck. On old VHS tapes that help give this current tale a timeless quality, the latter is played by Thomas Haden Church, who lends an energy boost to a draggy final quarter.

On sea and land, our Huckleberry friends are lightly hounded by the bad guys and followed closely by Eleanor, a volunteer nurse, or something, from Zak's ex-home. This is Dakota Johnson, who seems to have put as much thought into her character as the filmmakers did-which is to say, it was discussed maybe 10 minutes before each scene was shot.

Sadly, Eleanor is more a decorative reward for Tyler's good deeds than an actual character. But then nobody seems very thought-through, even with some obligatory flashbacks.

On the upside, LaBeouf is so physically present for his role, he appears to be growing, alongside gators and kudzu, right out of the Carolina and Georgia landscapes lovingly framed by True Detective cinematographer Nigel Bluck. And Gottsagen, though halting in delivery (and actually 34 years old), is likewise compelling.

The basic plot and dialogue will never win any Twain Prizes, but the visual storytelling here offers a raft of subtle pleasures.