In the 28th century, Valerian and Laureline are special operatives charged with keeping order throughout the human territories. On assignment from the Minister of Defense, the two undertake a mission to Alpha, an ever-expanding metropolis where species from across the universe have converged over centuries to share knowledge, intelligence, and cultures. At the center of Alpha is a mysterious dark force which threatens the peaceful existence of the City of a Thousand Planets, and Valerian and Laureline must race to identify the menace and safeguard not just Alpha, but the future of the universe.

When a faun named Mune becomes the Guardian of the Moon, little did he had unprepared experience with the Moon and an accident that could put both the Moon and the Sun in danger, including a corrupt titan named Necross who wants the Sun for himself and placing the balance of night and day in great peril. Now with the help of a wax-child named Glim and the warrior, Sohone who also became the Sun Guardian, they go out on an exciting journey to get the Sun back and restore the Moon to their rightful place in the sky.