Bonnie Nadzam's debut novel is more unsettling than it ought to be, given its familiar setup: A middle-aged man, thinking himself well-intentioned, abducts a girl. Who isn't exhausted with this plot in novels, movies and the news? But the differences in "Lamb" are important. There's little fixation on sexual obsession, as in "Lolita," and there are no visceral, thriller-ish displays of terror. "Lamb" is concerned not with lust and blood but a corrosive kind of neediness, and the book is as fascinating and unstable as the predator at its core.

That would be David Lamb, a 54-year-old man who has just buried his father and whose marriage has hit the skids. When he meets Tommie, an 11-year-old misfit who's teased by her peers, he sees somebody he can both rescue and control. Nadzam tracks David's thoughts about her as they shift from concern to contempt: "Not a pretty kid, not an athletic kid, not a smart kid. Just a skinny, slow-blooming kid desperate to keep up with her friends. Quick to make new ones. Stupid."

David soon cajoles Tommie into joining him on a road trip from Chicago to a family cabin in North Dakota. He pitches it as an adventure, albeit a funereal one. "Something to keep in your pocket when you're back in this place and forty years old and I'm dead and buried," he tells her, in a line that crystallizes the sadness and sense of loss that stalk him.

Unsurprisingly, the trip is disastrous for both: Tommie awakens to David's despair, David himself grows more delusional, and others begin to grow suspicious of the relationship between the two. "No one gets to have this, what we're having," David insists to Tommie, oblivious to the fact that nobody rationally pursues it.

Yet "Lamb" is in many ways a beautiful book. Nadzam's sentences are admirably clipped and controlled, nesting the emotional turmoil of its two subjects within the stability of their natural surroundings. References to sky, mountains and "stands of green-fingered oaks and red-beaded hawthorns and all the aspen" not only give the prose a loveliness the dialogue deliberately lacks, it also puts David and Tommie into perspective. Against this big-sky canvas, he's small and stunted, and she's sadly cowed.

Every abduction tale challenges the reader: It asks us to decide how much we're willing to sympathize with the abductor, because total monstrousness is uninteresting, if not unreadable. The chief emotion David evokes is pity, but Nadzam resists passing a simplistic judgment on him. Instead, her careful, spare prose leaves us to wonder how much harm he's done to himself and the girl he stole away.