The disillusioning ``education'' of a high-school English teacher takes center stage in this only moderately interesting melodrama from Nelson, the New Mexicobased author of three story collections and a previous novel (Talking in Bed, 1995). Thirtyish Birdy Stone, who has shrugged off both an unsatisfying engagement and a dead-end love affair, can't understand how she ended up in the depressed southwestern dust bowl of Pinetop, trying to interest her bored students in the books through which she herself lives a far more pleasing life. Inhaling marijuana with her gay colleague JÇsus helps some, but things really perk up when Birdy is hired by Isadora Anthony, who's writing a book (semi-literate) about the unexplained deaths of her daughter and husband in separate accidents a decade earlier--and especially when Birdy tumbles into bed with Isadora's teenage son (and her student) Mark. This may be Main Street revisited, and there's more than a little of Sinclair Lewis's Carol Kennicott in her, but Birdy knows she's no Cleopatra, and that the puppylike Mark Anthony, though he's cute and sexually inexhaustible, isn't the commanding hero who'll rescue her from her doldrums: ``Living in a trailer on the shady side of town, smoking pot with her best friend the homosexual, dating a seventeen-year-old ninny, investigating a teenage suicide.'' For Birdy is convinced she has ferreted out the truths about the Anthony family's losses. What she learns, however, is that unsolvable mysteries give depths to the lives of people whom she has formerly ignored or misunderstood. Nothing much happens here, and Birdy's hard-won illumination doesn't make her more appealing (her sense of humor comes and goes while her self-pity won't quit) in a story whose best moments are provided by supporting characters--like the cheerfully pregnant Luziana Rillos, a student whose earth-motherly presence kicks the novel awake every now and then. Nelson's longer fiction, at least as shown by this misfire, lacks the energy and concentration that distinguish her short stories.