Snow slabs that break loose can hit 130 kilometres per hour within seconds, burying anyone in their path before rescue is possible. This episode of the Deadly Disasters series examines why avalanches happen and why they remain so hard to forecast despite the warning signs mountains often give. It reconstructs the 2015 Mount Everest avalanches, triggered by the Nepal earthquake, which killed an estimated twenty-five climbers and injured roughly 360 people at base camp. The film then turns to the Alps, tracing a long history of slope collapses and settling on the 1950s 'Winter of Terror,' when a series of avalanches across Austria and Switzerland killed 265 people in a single season. Expert interviews, archival photographs, and footage of avalanche-prone terrain fill out the explanation of slab formation, snowpack instability, and the human decisions, from route choice to building placement, that turn a natural process into a disaster. The result is a grounded look at a hazard that keeps surprising people who should know better.