When a zombie virus pushes Korea into a state of emergency, those trapped on an express train to Busan must fight for their own survival.

Seong Soo, a twenty years old boy, decided to move to Seoul after being accepted into Seoul University. However, he was a victim of real estate scam. He then moves into his mother's friend's house. Moreover, it turns out that his mother's friend is a sexy self-employed mother and Seong Soo is attracted to her.

An innocent actress runs away from the scandal with an idol, the impudent idol that ruined her career, a passionate manager who is devoted to her and his ex-girlfriend who is now a sexy stewardess. These four that should never be together run into each other in an airplane. No one can run away and the most cheeky and erotic things happen here.

Hee-ran was a karaoke mistress when she first met Se-min through a marriage consultant company. He suggests they should have a contract marriage; she would get paid every month for being his wife and Se-gyu's mother. Hee-ran thinks this is a good deal but unlike her thoughts, being married is boring. Se-min only needs her at night and Se-gyu has a crush on Hee-ran who is like an older sister but hides it by being nasty. One day, Hee-ran meets Se-min's friend Tae-yeong and falls for him. In the end, Hee-ran and Se-min break up...

Dae-ho, Man-soo and Jae-kyeong gathered for a friend's wedding. The groom says he's buying so they drink their night away at a street stall. However, the groom doesn't show up and the other three talk about their sex fantasies while they wait...

Two police stations from neighboring precincts are in constant fierce competition with each other, including for the Officer of the Year award. But then a high-profile case forces them to work together.