Right after a bulldozer has uncovered and displaced an ancient picture rock that had been blocking the entrance to a cave-like mound on the Nelson's farm, the animals--theirs and neighbors--begin to run amok; pets run off or bite their owners, and one old lady is found clawed to death by her cats. The connection? It seems that the rock was a sort of magic door that kept the ancient, legendary Weendigo, or Spirit of the Wild, imprisoned in another world. And when the Nelson children--Amy, eleven, and brothers Jeff and Craig--take a writer friend and his friend an anthropologist to see the cave, they meet the Puk Wudj Ininees, little ""Indian elves"" who report that only ""a certain kind of girl, neither married nor too young,"" can lure the Weendigo back to the cave. Otherwise, as anthropologist Deer explains at earnest length, our world of penicillin, electricity, plenty of food--civilization itself--will be replaced by savage lives that are ""dangerous, miserable and short."" It is Amy of course who must and does serve as the Weendigo's bait, fighting its compelling attraction with the multiplication tables and rallying at crucial moments to the urgings of Dr. Deer--who cuts the excitement considerably, even for those who find arithmetic a satisfactory answer to the call of the wild, by running along beside her. A more serious damper, though, is that McGowen's slight story just can't support his heavy theme--which, in any case, is as dubiously one-sided as the primitivist romanticism he evidently intends to refute.