“Lamb,” adapted from Bonnie Nadzam’s novel, explores David Lamb’s journey of self-exploration after his marriage falls apart and his father passes away. In an effort to restore his belief in his own virtue, he focuses on Tommie, an awkward and socially isolated eleven-year-old girl. Lamb believes he can steer her away from a future of indifference and void, so he embarks on a road trip with her from Chicago to the Rocky Mountains, intending to introduce her to the splendor of the natural landscape. This expedition impacts both of them in unforeseen ways.