Tom and Jennifer, a brother and sister, make an easy passage between the adult world of scepticism and the world of children which admits the wonderful and awesome. On a visit to their grandmother's home on the California coast, they become embroiled in a search for a prehistoric survival. And at that eerie time of monster. A vivid atmosphere permeates this book which as in the author's previous Mushroom Planet stories and Mr. Bass' Planetoid combines scientific data with skillfully administered imagination.