The world has been reduced to rubble by a massive earthquake. While no one knows for sure how far the ruins stretch, or what the cause of the earthquake may be, in the heart of Seoul there is only one apartment building left standing. It is called Hwang Gung Apartments. As time passes, outsiders start coming in to Hwang Gung Apartments trying to escape the extreme cold. Before long, the apartment residents are unable to cope with the increasing numbers. Feeling a threat to their very survival, the residents enact a special measure.

After losing her laundry store to a fire incident, a single mom Duk-hee receives a call from a bank offering a generous upfront loan so she takes it right away. But soon after, she finds out that she has become a victim of a voice phishing scheme. Devastated, Duk-hee turns to the police for help, only to be more disappointed that there is no hope of retrieving her money. At the moment of despair, Jae-min, the phisher who tricked her, rings her phone once again to tip Duk-hee off about the criminal organization that locked him up and coerced him to make voice phishing calls from China. With that call, Duk-hee makes up her mind to investigate this case for herself and take a plane to China with her friends.

In Beirut 1986, during the Lebanese civil war a Korean diplomat is taken hostage without a trace. Two years pass and long forgotten, a young diplomat Min-jun receives a phone call proving that the hostage is still alive. With the given mission, Min-jun is sent to Beirut to save the hostage with a bag of ransom money.

After spending a decade in prison, a hitman learns that he has a daughter and just wants a chance at a normal life. But his former mob boss wants him back at any cost, sending merciless assassins after him.

Kim Dok-ja, an ordinary man in his 20s, is the only reader of an obscure web novel titled "Three Ways to Survive the Apocalypse". After having read the last chapter, the novel suddenly becomes reality, and its omnipotent hero Yu Jung-hyeok appears before Kim. As the only person who knows how to survive in this world, Kim and his companions strive to save the world by writing his own, new ending.

When a raging flood traps a researcher and her young son, a call to a crucial mission puts their escape — and the future of humanity — on the line.