Snow-covered mountains, narrow valleys and endless forests mark the Rocky Mountains in northern British Columbia in Canada. Untouched wilderness and popular skiing resorts can be found next to each other. In winter, the risk of avalanches is extremely high. Regional cities, streets and railways are endangered. The avalanche guardians work under exceptional circumstances: with canons they shoot into slopes, or they dare risky operations in helicopters in order to drop highly explosive charges. Often they risk their lives in order to protect the lives of others. What seems to be brutal at first sight is an essential part of one of the biggest and most modern avalanche prevention programme in the world.