An expedition team accidentally triggered a device left behind by aliens on Earth while exploring an underwater cave, which set off a series of bizarre events. The aliens find Li Chenlong, hoping he will help them return to Planet Sairo, because Li Chenlong's ancestor was once gifted a "key" by the aliens' ancestor—a key that can activate the "Forbidden Book of Heaven" device. Consequently, Li Chenlong and the aliens embark on a bizarre and perilous journey to find this "key."