Mont Blanc is one of the world's most popular destinations for Alpine climbers and scientists. NOVA follows a team of daring "glacionauts" as they descend into a labyrinth of unexplored ice caves to find trapped flood water that menaces the populated valleys below.

Mont Blanc is one of the world's most popular destinations for Alpine climbers and scientists; no other peak has such a long record of mountaineering and glaciology. But 200 years of winter sports, science and tourism have done nothing to tame this mountain. The hazards generated by rock falls, ice avalanches and sudden flooding are still poorly understood and almost impossible to control. NOVA follows a team of daring "glacionauts" as they descend into a labyrinth of unexplored ice caves to find trapped flood water that menaces the populated valleys below.