After a meteor-like object lands in the woods, poachers unearth a cave filled with alien eggs. As they attempt to destroy the eggs, one of them is killed by an unseen creature, leaving one egg intact. A young boy named Tommy finds the remaining egg and brings it home to hatch. As more murders occur around town, Tommy learns that his new pet alien, who he names Trumpy, possesses telekinetic powers.

Like in the novel of Jules Verne four persons try to get to the centre of the world by entering into a world of caves by a volcano. On their way they discover among other things also prehistoric animals like some dinosaurs.