On an ordinary forest night, the mother bear, who loved the little bear and the little bear, left them after a fire, and the two bears were very sad. In the twinkling of an eye, shaved head strongly took Xiong Da Xiong II to Zhenxing Island to visit the Robotics Research Institute, but accidentally got a clue from the mother bear, so Xiong Da and Xiong er explored all the way. Why did Mama Xiong leave without saying goodbye? Will the two bears finally find their mother? What's the story behind the fog? All the mysteries are waiting to be revealed.

一個普通的森林夜晚，對小熊大、小熊二寵愛有加的熊媽媽，在一場大火後離開了他們，兩熊心碎不已……轉眼多年過去，光頭強帶熊大熊二前往振興島參觀機器人研究所，卻意外得到了熊媽媽的線索，為此熊大、熊二一路探尋……熊媽當年為何不告而別？兩熊最終是否能找到媽媽？迷霧重重的背後還有怎樣的故事？一切謎團等待揭曉。