A cross-country streamliner is wrecked in the Rocky Mountains and the valuable show dog, Baron, that Jean and Louise Dana are taking to his new owner in New York disappears from the train. Searching by horseback for Baron, the girls encounter exciting adventure and a challenging new mystery.

Baron's tracks lead toward Lost Lake, near the site of an isolated community buried in a mountain landslide forty years ago and now reputedly haunted by a witch. A nefarious plot against the witch manifests itself in bizarre clues: a threat chipped in stone in an ancient Indian cave and a message -- "Get the witch!" -- sinisterly triple-echoed in a rugged canyon.

As Jean and Louise, assisted by a friendly rancher, diligently search for the handsome German shepherd dog, they try to fathom the mystery of the legendary witch and her unknown enemies. Who is this weird figure? Why does she frequent the site of the old disaster? Most important of all, who are the evil schemers pursuing her -- and why?