Paul’s existence depends on walking, sitting in cabs, flying on planes, riding in the backs of cars. Like his constant presence online — Lin shows us Paul and his friends G-chatting, e-mailing, tweeting, checking Facebook — he’s always either somewhere other than where he just was, or on his way to somewhere else. Here Lin is reminding us of an interesting fact about contemporary life: physical travel has become almost as effortless and ­commonplace as cyber travel. Which might mean we aren’t so much distracted as we are always running away from home.

Travel has traditionally been a way for people to realize that their own perspectives are limited, that there’s more to the world and other people than they’d assumed. Travel helps you to mature; thus the tradition of the “wander-year,” on which this novel depends. And for a time we worry that nothing will break through the icy superficiality that characterizes the lives of Paul and his friends — not so dissimilar from the superficiality of Jake and his crowd in “The Sun Also Rises,” but here Xanax and Ecstasy take the place of Burgundy, Champagne and gin. Yet by the time Paul and Erin are in Taipei, we notice that something different is happening to them. Rather than talking about, they start talking to. They start listening. During a long and intimate discussion of their sex lives, Paul finds himself focusing on their “conversation, which was producing its own, unmediated emotions.”

Most of us take it for granted that we should focus on our conversations and the emotions they produce. But we take it for granted while sitting in a restaurant with a spouse, sending texts or checking Facebook or Googling the movie we’re going to see. Slowly, without pretending to have any great breakthroughs, Paul and Erin start to love each other more; they start to become more involved, more aware, less superficial. They find themselves doing things, rather than merely watching things. For the aptly named Paul, a conversion is on its way: life is changing from the aesthetic to the ethical. Like Lin’s simple but never flat prose, his characters have become authentic.

Lin is, however, also suspicious of notions like sincerity and authenticity, and Paul is reluctant to let go of the protective irony that has defined his youth. The real threat to him is love: “He wanted to move backward and close the door and be alone again, in the bathroom, but Erin had already noticed him and, after a pause, distracted by her attention, he reciprocated her approach. They hugged a little, near the center of the room, then he turned around and moved toward the kitchen — dimly aware of the existence of other ­places, on Earth, where he could go — and was surprised when he heard himself, looking at his feet stepping into black sandals, say that he felt ‘grateful to be alive.’ ”