On an ordinary forest night, the mother bear who doted on Little Bear Da and Little Bear Er left them after a fire, and the two bears were heartbroken... Many years passed in a blink of an eye. Bald Qiang took Big Bear and Little Bear Er to Zhenxing Island to visit the Robotics Research Institute, and unexpectedly got a clue about the mother bear. For this reason, Big Bear and Little Bear Er went all the way to find out... Why did the mother bear leave without saying goodbye? Will the two bears find their mother in the end? What kind of story is behind the fog? All the mysteries are waiting to be revealed.