Byung-gu believes that all of the earth will be in danger because of the evil doings of aliens. That's why he knows that unless he can meet the prince from Andromeda before the total lunar eclipse, planet earth will be in grave danger. In order to meet the prince, he must find an extraterrestrial living on earth. So Byung-gu kidnaps the most logical suspect for being an alien, Kang Man-shik and asked him to allow meeting the prince. The battle between Byung-gu, who's trying to uncover a secret alien plot and Kang Man-shik, who thinks Byung-gu's nuts and is trying desperately to escape.
Jang Joon-hwan started studying film at the Korean Academy of Film Arts. As soon as his graduate film 2001 Imagine received favorable comments at multiple film festivals including the Clermont-Ferrand, the San Francisco and the Vancouver International Film Festival, he caught attention. He also managed lighting for Transmutated Head, directed by Ryoo Seung-wan and Incoherance, directed by Bong Joon-ho. Save the Green Planet! is his feature debut film.