A group of five friends gets caught in an avalanche in Lyngen, Norway, in March 2022. Once member dies, three have varying degrees of poly-trauma injuries and one is mostly unscathed. Everyone in the group is an experienced mountaineer, one is even an avalanche forecaster and another a ski-guide in Austria. All of the group has often had to make decisions with incomplete data regarding risk versus reward in the mountains. The decisions which were made that day were obviously thought to be acceptable at the time. How did they get it so terribly wrong? This lecture explains the thought process and decisions that were made and then reevaluates them with the benefit of hindsight to find learning points.