In a South Korean family's joyful celebration of an astronaut's wedding, the newlywed receives a distressing call to join a reconnaissance flight. The mission observes a nuclear test, triggering an earthquake that mysteriously shifts its epicenter towards Seoul. Authorities are alerted by a photographer documenting the destruction, who claims the cause is a massive underground creature, Yongary, heading towards the city. As the creature emerges, it unleashes chaos on Seoul, and is seen fueling its fiery breath by drinking from refinery storage tanks. An eight-year-old boy, Icho, notices Yongary's aversion to ammonia, which his scientist boyfriend recognizes as a key to defeating the monster. They concoct a stronger ammonia-based solution, which is airlifted to deploy against Yongary.
Yongary, Monster from the Deep
A prehistoric reptile, fueled by gasoline, wreaks havoc in Seoul after a series of earthquakes in central Korea, causing a city-wide rampage.
