In several respects, John Wray’s “Godsend” (Farrar, Straus Giroux) appears to be a conventional specimen: a compact, tautly written novel of travel and growth, about a troubled eighteen-year-old California woman who leaves home and sets out on an arduous, sometimes terrifying journey. Formally, everything fits into place: lean dialogue, attentive description, nicely paced interiority, deft characterization—all the right contemporary rations. Wray’s publisher calls it “a coming-of-age novel like no other,” and the reader prepares for a decent chunk of Californian Bildung. But Wray’s story is in fact indecently unconventional. Our heroine leaves not for, say, New York but for a madrassa in Pakistan, and then joins the Taliban, across the border in Afghanistan. She “grows,” she comes of age, but the journey will strike most readers as a distinctly unsentimental education. “Godsend,” which begins like a recognizable combination of bildungsroman and adventure tale, becomes much stranger and more original after it arrives in Pakistan, discovering within itself a profound understanding of the demands of religious practice—of religious submission, especially—which has eluded almost every serious contemporary American novelist since 9/11. It is not only Wray’s heroine but also his novel that comes of age, steadily deepening and astounding as it develops.

“Godsend” opens, as perhaps it must, like a thousand other contemporary fictions. Aden Sawyer, the teen-age protagonist, has a boyfriend, Decker Yousafzai, and an unhappy family: her mother, an alcoholic, and her father, a remote and sententious professor, whom Aden scornfully addresses as “Teacher,” are separated. Restless, superior, and vengeful, Aden is on the verge of escaping her despised Santa Rosa landscape: “She walked down Hidden Valley Drive to the cemetery, past Carmen’s Burger Bar, past Ramirez Pawn N Carry, then up Pacific toward the junior college. On Mendocino she stopped in front of a shop window and shaded her eyes and looked in through the glass. . . . Some kids from school walked by and snickered, and she allowed herself, for the last time, the luxury of picturing them dead.”

But something of the novel’s difference can be found in these early pages, too. Aden is a recent Muslim convert who can speak Arabic, and Decker is an American of Pashtun origin. Aden is bidding a sour farewell to her parents before leaving, with Decker, for Peshawar, where a cousin of his lives. It is, we gather, sometime in the summer of 2001. Her father, who teaches Islamic studies at Berkeley—one senses that this is hardly incidental to her particular path of adolescent rebellion—warns her against the journey, although he thinks that she is travelling to the Emirates, to study. Why won’t she listen to him? Islam, he says, teaches deference to one’s elders, reverence for the father. “Not if the father is an apostate,” comes the freezing reply. Wray’s novelistic efficiency, which might, with other material, constitute a limiting conventionality, is here a provocative withholding. John Updike, in his novel “Terrorist” (2006), felt the need to establish the fiery Muslim credentials of his protagonist upon all-too-visible kindling: within the first three pages, we encountered him walking down a New Jersey street thinking about the Prophet and the ninth sura of the Quran. Aden’s peculiar disaffections and devotions emerge more naturally, out of secular American banality, and are presented, at this stage, without descriptive commentary; the reader has to catch up. As Aden and Decker approach the San Francisco airport on a bus, they have this very brief exchange:

—Did we miss our one o’clocks?

—It’s okay. We can pray when we get out.

Inside the airport, they find an interfaith chapel next to a food court and lay out their prayer mats. Wray enjoys the irony—gently sustained throughout the novel—that the young man named Yousafzai is far less religiously zealous than the young woman named Sawyer. He’s taking the trip for the adventure, and because he is besotted with his girlfriend:

—How do you know that’s east, Sawyer? There’s no windows in here.

—It’s east.

He nodded dubiously. —We’re praying at the food court, basically.

—I’ll tell you what I’m going to do, Decker. I’m going to go ahead and say the prayer we missed. What you decide to do is totally your call. . . .

—So long as you’re happy. I think this is south.

There are intimations of Aden’s burgeoning dogmatism. On the plane, she tells another passenger that she wants to see Afghanistan, because it’s “a place ruled by believers. A country full of people living by the word of God.” She tells Decker that she is not sure she will be going back home, and announces that she’ll no longer have sex with him. Aden also begins dressing as a boy, with a crewcut and her breasts tightly bandaged. She passes for a male teen-ager; she knows that madrassas routinely take young boys. But, again, Wray doesn’t press down on these alterations, preferring implication and gesture to dragging explication: “She reached up sleepily to arrange her bangs and was surprised for a moment to find her head shorn.” After landing in Karachi, which disappoints Aden, she and Decker make their way by bus to Peshawar, “no less abject” than Karachi, she thinks, but still discernibly “the holy fortress it had been.” A taxi takes them to a village about two hours outside the city, a place that “looked like a child’s or an idiot’s rendering of a town: high mud-walled compounds, bowing outward and cracked at the corners, with pale blue gates of corrugated steel.” There, a very young boy leads Aden by the hand into the madrassa’s compound, and a new life begins.