There's often a fine line between heroism and foolhardiness, as in the deaths in 1969 of five young Montana climbers (ages 18 to 22) who, against the advice of professional rangers, made a winter attempt on treacherous Mt. Cleveland in Montana's Glacier National Park and succumbed to an avalanche. In an engrossing tour de force, Jenkins, a former Atlanta Journal-Constitution staff writer, re-creates this tragedy and also seamlessly interweaves a wealth of avalanche lore, science and history. Jenkins, writing in crisp, clean prose, fashions a deeply personal tale out of their adventure. One of the five, Jerry Kanzler, an accomplished climber, was still recovering emotionally from his father's 1967 suicide; a certain bravado and desire to prove his manhood seems to have motivated him as well as his companions. Jerry's brother Jim, a ski instructor, risked his life trying to find and save the missing five, but it would take rescuers six months to locate the bodies. In 1976, to honor his brother, Jim Kanzler and two friends became the first climbers ever to scale Mt. Cleveland's steeply vertical north face. Jenkins, who teaches writing at the University of Delaware, probes the metaphysical roots of mountaineering, spins tales of avalanches from Peru to New Zealand and covers the latest advances in avalanche science. He also explores avalanches in history, from Hannibal's devastating loss of men and horses in the French Alps to the WWII heroism of U.S. Alpine ski troops, who helped Allied forces capture German strongholds in the Italian Apennines. Photos. Agent, Neil Olson, Donadio & Olson. Author tour. (Feb.) FYI: Jenkins is editor of the forthcoming The Peter Matthiessen Reader (Vintage).