Marchlands, Karla Kuban's debut novel, began as a short story and probably should have stayed that way. What might have been a tight, no-nonsense evocation of an unusual setting—a desolate 2,000-acre sheep ranch in Wyoming—is instead stretched into a tiresome coming-of-age tale with manipulative twists and annoying poetic lapses. That's especially unfortunate because Sophie Behr, Kuban's 15-year-old narrator, is a fascinating creation, tough-minded and intellectually curious but not immune to the pitfalls of adolescence. Squirming under the thumb of her alcoholic, religious-zealot mother—who stares blankly at TV newscasts all day looking for shots of her son in Vietnam—Sophie finds comfort only in her beloved horse and in the silver camper of a young Mexican shepherd, the father of her unborn child. Confused about who she is and what her future holds, she runs off in search of her long-absent father and discovers a dark family secret. This revelation, though it comes perilously close to reducing life's mysteries to the level of pop-psychology, is by far the most riveting passage in Marchlands, and it illuminates the book's central flaw: Sophie's clipped, matter-of-fact narration has its advantages, particularly in its unflinching depiction of teenage sensuality, but Kuban is too often handcuffed by it, unable to expand into richer and more penetrating insights. There's no question that Kuban is a promising novelist, but in this first search for an authorial voice, she writes herself into a corner.