Caroline Pignat’s “Wild Geese” is a follow-up to “Greener Grass.” It tells the story of Kit Byrne and Mick O’Toole’s trek to North America from famine-stricken Ireland. Despite the difficulties, Kit is committed to finding her family, even if it means letting go of her feelings for Mick. The story of Kit represents all Irish expatriates, and the title “Wild Geese” refers to them all.