From the publisher:
Another exciting adventure for this happy family comes about through their new friend Indy Roades, a former baseball player and a Yumatan Indian. He tells them about his pueblo in the mountains of New Mexico, and his tribe's lost turquoise mine. When Mr. Hollister hears that a store there, called The Chapparal, which sells silver trinkets and Yumatan articles, is closing down, he considers buying the goods for his own shop, The Trading Post. He decides to go to New Mexico to examine the stock, and takes his family along with him.
After an exciting journey by plane, and in a rented school bus, they arrive among the friendly Yumatans. The children have a wonderful time joining in the games and festivals. Indy's niece and nephew, Blue Feather and Red Feather, show them how to shoot with bows and arrows, and ride bareback on Pinto ponies, as Indian children do. But best of all, they foil the thieves who had stolen the goods they came to buy--and discover a clue to the buried mine. How they help the tribe to regain their prosperity and happiness, and the reward that the grateful Yumatans give them in return, makes an enthralling end to this new story in the Happy Hollister series.