In Beyond Mammoth Cave: A Tale of Obsession in the World's Longest Cave, James D. Borden and Roger W. Brucker provide gripping first-person accounts of the discoveries, including Roppel Cave, that made Kentucky's Mammoth Cave three times longer than any other cave in the world. Borden, a relative newcomer, and Brucker, a veteran explorer, bring a personal and sometimes conflicting view of their roles as adversaries in a race...