Lamb traces the self-discovery of David Lamb, a narcissistic middle aged man with a tendency toward dishonesty, in the weeks following the disintegration of his marriage and the death of his father.
Hoping to regain some faith in his own goodness, he turns his attention to Tommie, an awkward and unpopular eleven-year-old girl. Lamb is convinced that he can help her avoid a destiny of apathy and emptiness, and even comes to believe that his devotion to Tommie is in her best interests. But when Lamb decides to abduct a willing Tommie for a road trip from Chicago to the Rockies, planning to initiate her into the beauty of the mountain wilderness, they are both shaken in ways neither of them expects.