Zhang Fan was attacked by aliens one night, and only escaped with the help of a janitor named Ah Le and a mysterious woman named Anna. Both of them claimed to be spies from the “Related Department“, who were responsible for taking care of aliens. They told Zhang Fan that he used to be one of the organization's top spies, “Agent Z“. Now that the earth is under attack from aliens, the only thing that can save the world is Agent Z's “Cube“. But Zhang Fan soon finds that they also have ulterior motives. Having lost his memory, he must simultaneously recover it and also find clues from previous videos. After finding the “Cube“, Zhang Fan realizes that Ah Le is an alien disguised as a human, and Anna is an extreme spy who wants to kill all aliens. They both used Zhang Fan in order to reach their goals. Zhang Fan smartly solves their conflict during their standoff, but soon discovers that there is even bigger power in the shadows...