What is the plot in the book Whirligig?

Brent Bishop attends a private high school in the Chicago area. One night he goes to a party thinking to impress a girl. When his plan backfires, he loses his temper and attempts to drive home drunk. He causes a car accident that kills another high school student. In order to atone for his crime, he is asked by the victim’s mother to build versions of her favorite wooden toy, a whirligig, and to install them in the four corners of the country: Washington, California, Florida, and Maine. For the rest of the story, Brent rides a Greyhound bus from one location to the next, building and erecting the required whirligigs. Along the way, he learns much about traveling, woodcraft and tools, the countryside, other people, and most of all, himself.