At home in California's High Sierras, Prof. Clifford Groves (Robert Shayne) hears glass breaking and looks up in fear from his book, ''Neanderthal Man and the Stone Age''. He finds his lab window smashed and room wrecked. His adult daughter Jan (Joyce Terry) is awakened by the noise. Groves sends her back to bed, telling her that he has to go to attend to business.