The Cave (The Wind Cave Book 1‪)‬

When a nuclear war devastates the U.S., a four-day excursion quickly turns into a fight for survival in The Cave. Six Stanford students journey into one of the deepest and longest caves in North America. A day into their journey, a nuclear war begins from within the U.S. Unable to return to the surface, and unsure what they will find when they do, the Cave will test the strength and survival of each person differently - transforming six individuals into a team, and ultimately...a family.