As humans turn into savage monsters and the world plunges into terror, a handful of survivors fight for their lives — and to hold on to their humanity.

Years after filming a viral documentary in high school, two bickering ex-lovers get pulled back in front of the camera — and into each other's lives.

Taek-il recklessly leaves home, defying his mother who asks him to go to college. In the unfamiliar neighborhood, he happens to get a job as a delivery man for a Chinese restaurant. And he mingles with new people such as Geo-seok, a chef, and Kyung-ju, a boxer. Meanwhile, Sang-pil, a friend of Taek-il, enters the private loan business to make money. At first, it seems easy to make a big fortune, but soon he finds himself in pain as he faces unexpected things.

Lee Chung is a Prince of Joseon, but he has been taken hostage to the Qing Dynasty. He enjoys boozing, womanizing and gambling. He is also an excellent swordsman. His older brother Lee Young will succeed to the throne and brings Lee Chung to Joseon. He returns after more than 10 years. Soon, Lee Chung faces monsters that run rampant in the night.

Dae-soo and Mi-ra have Ah-reum when they are 17. Ah-reum is diagnosed with progeria, and as his body rapidly ages, his finds comfort in writing a story about how his young parents fell in love.