This is a splendid fantasy about five youngsters who discover dinosaurs in the middle of the jungles of Peru. The adventure starts when the five, whose families are making a business trip to South America, are taken to a little-explored cave and are separated from their guide by a rock-fall. In their wandering they come upon a valley within the cave which is literally crawling with prehistoric monsters, giant ferns, and cave men. Under the leadership of the 14-year-old Andy they manage with great aplomb to surmount all the complications involved (for instance an intruding dinosaur is chased away with flash bulbs). The plot is totally improbable and completely enjoyable.