Professor Lindenbruck proposes to make an expedition to the center of the Earth to follow the trail of a missing scientist. Her thirteen-year-old daughter Mexa insists on going along and wants to take her piglet from India, too. Gower, Mexa's new friend, also decides to join the expedition and everyone enters a fantastic world of rare beauty and a lot of danger ... Underground, where prehistoric animals and a lost city await them. But, the great adventure becomes a hunt, when the rival scientist Dr. Greed, does everything to stop them aided by his ally, a smart bat and the terrible Crunch.