Do-gyeong jumped in to save his student Jiyong from drowning. After the two pass away, Myeongji, Do-gyeong's wife, and Jieun, Jiyong's sister, are left alone in the world, having to cope with the loss of their loved ones. Myeongji travels to Warsaw, Poland, to avoid her harsh reality. She meets an old friend and hides her husband's death as if trying to reject the tragedy....
Five members of the mountain bike club, Sangaja. To ride a mountain bike, we head to Chiaksan Mountain, where Min-joon's Uncle villa is located. After arriving at Chiaksan Mountain and enjoying the ride, strange things began to happen to the party…. And something unidentified chasing them! A desperate survival game for Sangaja's party to survive on Chiaksan Mountain begins....