Phil joins Craig during a book tour in South Korea, through Seoul and Bucheon, then extending to a research journey in rural Geumsan, the epicenter of Korean ginseng cultivation. Geumsan is the sister city to Marathon, the brothers' tiny American town, but with a deep thousand-year history of art, mythology, and cuisine surrounding the medicinal root. While there, the brothers sort out how Craig's paralyzing writer's block and Phil's marital strain are tangled up in their working-class childhood.