An unearthly roar. A blinding blast of white. With no warning and in mere seconds, an avalanche--with the power of up to 200 pounds of TNT--wipes out everything in its path. One team of scientists hopes to better understand this deadly force by triggering an avalanche onto themselves. But even those who study them can’t precisely predict the size of a slide, and they find themselves buried alive in their research shack.

Witness this and other terrifying avalanches, from the ski slopes of Montana to Juneau, Alaska, to the village of Flateyri, Iceland, to Switzerland’s most vulnerable mountain roads. Claiming hundreds of lives each year, avalanches respond to a simple combination of snow, slope, and gravity. But the effort to control them is greatly complicated by the precarious dynamics of the snow pack--and the stubborn persistence of humans intent on playing or living in their path.

See the extremes the experts are going to to protect us: measuring the strength and velocity of snow out on slopes and in labs; building deflecting walls; shooting explosives that trigger controlled avalanches to keep recreational areas safe. And meet some shaken survivors who have been crushed under a wall of snow yet lived to tell about it--this time, at least.