"Jobless, 30-something Yong-nam has nothing going for him in life, but at his mother’s big 70th birthday celebration, he accidentally stumbles into Eui-ju, his old friend and secret crush from a hiking club back in the college. The two immediately rekindle their old friendship, and all is joyous until a mysterious gas seeps into the building and, before long, shrouds the entire district with toxic gas. As panic breaks out, Yong-nam and Eui-ju use their experience and knowledge from hiking in college to help evacuate people from the building and save themselves. "