"Sioux City" has the rough outline, at least, of a murder mystery, one in which Lou Diamond Phillips, as a half-Lakota, L.A.-bred yuppie, retreats to the Native American reservation of his birth to solve the puzzle of his natural mother's sudden demise.
We're not talking Tony Hillerman here. This is the kind of agenda-heavy, culture-celebrating picture that has the hero solving the mystery not by gathering clues but by going on a vision quest where the twist is mystically revealed to him, an hour or more after it's occurred to the sober audience at large. Such sweat-lodge shorthand frees the rest of the movie up for plenty of reverential luxuriation in the Lakota lifestyle and lots of loving glances between Phillips and Salli Richardson, the knockout beauty he finds in his first hour on the Brown Rocks reservation.
Phillips--who directed as well as starred--clearly thinks he's doing the Lakotas a favor with his respectfulness, when he would've better honored them by holding out for a halfway-tenable script. As is, L. Virginia Browne's screenplay has Phillips' newly discovered grandfather sagely chastening the citified hero with platitudes like "Time has no meaning in the healing process," when all he did was ask how long he'd been knocked out from a beating. Administering the blows are Sioux City's local white cops (played by Bill Allen and grizzled Ralph Waite), whose racist menace is so overt the plot can only pay off in inevitabilities.