For Miguel Arteta’s new film, an affecting Jennifer Aniston forsakes the plucky, material-girl bite of Friends’ Rachel for the worn-down Texas cadences of Justine, a depressed cashier at the Retail Rodeo, a discount store a couple steps down from Wal-Mart. Like Arteta’s previous effort, Chuck & Buck, The Good Girl aims for dark comedy but winds up merely dark.

Justine hates her life, her boring job giving hideous makeovers to old women at the Rodeo, and her pot-smoking husband (John C. Reilly), who spends every night with his best friend, Bubba (Tim Blake Nelson), zoned out on the couch. Then she meets Tom (Jake Gyllenhaal), who calls himself Holden (Tom’s my slave name, he explains, in the film’s one real laugh), a would-be writer who’s just as depressed as she is. They embark on a passionate affair; eventually Justine must choose between her husband and her lover, conformity and rebellion. The cast, which includes Zooey Deschanel and Mike White (who also wrote the screenplay) as fellow employees at the Rodeo, is uniformly terrific, but that can’t save The Good Girl from sinking into a funk. (93 minutes)