Young-gu hides in a cave during a game of hide-and-seek. There he finds a humongous dinosaur egg, which soon hatches. The baby dinosaur, Dinosaur Zzu Zzu, wanders around and is saved by Young-gu. They become fast friends. Running from the police and thieves who are after the dinosaur, the two friends hide in a cave but are soon found out and captured. At that time, Zzu Zzu's mom comes to Seoul to find her baby. Chaos and mayhem ensues and the army is sent out to stop the dinosaur. A tremendous battle between the Zzu Zzu's mom and the army takes place and although she rescues Zzu Zzu and Young-gu from the thieves, she is killed by air force's missile. Despite Young-gu's pleas to stop, the police shoot at Zzu Zzu. Zzu Zzu saves her own life by faking her death.
