A working class family move into a new condo purchased after 11 years of hard work. They throw a housewarming party to show his co-workers when overnight a heavy downpour creates an extremely deep sinkhole that engulfs the entire building.

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....

"Sinkhole" is about what happens when a newly built villa falls into a sinkhole with its residents trapped inside. The residents' families and emergency services attempt to save them. The main character, Park Dong Won is a man who finally buys his home after 11 years, only to have it fall into a sinkhole within a minute. Along with Dong Won, there's also Kim Seung Hyun, who ends up getting stuck in the sinkhole with him, who is his supervisor at work. With them is also the Chungwoon Villa resident, Jung Man Soo, who works multiple part-time jobs to raise his son as a single dad.