In the cold winter, a group of Shenzhen tourist families take a trip to the northeast Changbai Mountain. It was originally intended to be a happy and harmonious holiday, but due to the negligence of his father, an 8-year-old boy is unfortunately lost. The parents seek the help of the local authorities, and the search and rescue operation begins immediately. The golden rescue time of 24 hours passes, followed by the routine safety limit of 48 hours, but the child is still nowhere to be found. Even if there is little hope, the father and the search and rescue teams will not give up.