The Underground is real and it has been in the shadows for too long; at least, that is what some people seem to believe. Joonmyeon gets a dead centaur spouting prophecies in his room, hence chaos. Plus, it seems like his pack can control wind or something.

With the help of two clueless, rogue Agents, the pack must find a siren to tell them what to do, or else an evil Titan lord will take over the world (destroy it, was more like it). Also, Kyungsoo and Jongdae need to get their together.