Synopsis：The educated urban youth, led by Hu Bayi, went and worked in the countryside of Northeast China. To rescue the sick villager——Huamei, they, together with the hunter, Uncle Zhao, went to Forest and Snow Bear Cave to collect antidote. However, they were suddenly attacked by a bear, so they had to flee into the underground Weasel Mansion. They witnessed strange things and illusions happen there. Hu Bayi and other youth, not bewitched by superstition and tricks, found the real criminal step by step. And they finally escaped from the underground mansion and saved the villagers.