In a modest suburb in the San Fernando Valley, laced with highways and studded with parched little palms, Tobe (Evan Rachel Wood) is a typical motherless teen. She fights with her dad, worries over her little brother, and bares milky adolescent flesh that miraculously never tans or scalds. Into this closed world comes a man who is an exception to all the known rules. Harlan (Edward Norton) materializes near an overpass with lasso in hand, like some kind of extraterrestrial shape-shifter who learned about American culture by watching Westerns. He isn't an alien, unless aliens can bang pretty girls in their fathers' hallways, but he's about as odd and unpredictable.
There are two strains in this flawed but absorbing film, one obsessively aware of its sources and the other blithely unexamined. Down in the Valley fancies itself a post-Western, and all of its energy goes into this theme: Norton's performance as an anachronistic gunslinger is ragged and formidable, and the camera observes the way the exurbs encroach on the desert (and vice versa) with an impartial eye. But there's just as much Lolita in its tale of flushed love, and the filmmakers pay this strain little mind. Why does Tobe seduce a strange gas attendant through a rear car window? Just because.
The Western portion of the movie gets overly literal at times, from an altercation on an Old West movie set to liberal quotations from iconic movies, but the final shootout in a half-constructed development makes it all worthwhile. There's something creepy about the hollow shell of a house with an expanse of desert in its backyard.