When the Alden children accompany their grandfather to the Snow Haven Lodge, a series of odd occurrences threaten to disrupt the annual winter games.

The Alden children, isolated in a storm at a small bus station, are led into a mystery centering on a polluted river.

While visiting a Navaho Indian reservation in New Mexico, the Aldens try to save a forest under threat of development by proving it is the site of a lost, buried village, but someone is sabotaging their dig.