The Outdoor Girls initiate three new members, Carolyn Cooper and twins Meg and Lota Bronson into their group. Meg immediately suggests a vacation at her Uncle Dan's New Moon Ranch, and this proposition is met with approval. Before the girls depart, Meg and Lota overhear an argument between Uncle Dan and two strange men. When the girls question Uncle Dan, he refuses to give details. Meg and Lota become even more concerned after spotting the same two men at the train station in Chicago. What do the men want?