Park Dong-won (Kim Sung-kyun) a common man and his family move into a house purchased after 11 years of labour. They throw a housewarming party and invite all friends. A heavy overnight downpour creates an extremely big sinkhole and in a mere minute it engulfs the whole house with the people inside it. Deep down the hole Park Dong-won his neighbor Jeong Man-soo (Cha Seung-won) and the guests have to find a way out. As the luck would have it rain again begins to pour down filling the sinkhole with water. They must find out a solution before time runs out to survive....