In this, the fifth book in the bilingual Palo Alto adventure series, Juanita and her friends excitedly meet the first truckload of horses for the new Hacienda Palo Alto equestrian center. Her hopes of becoming an accomplished equestrian like her famous cousins are dashed by the controls set upon her by her guardian stepfather and by the ensuing battle he started between two rival television stations, both who want to film the opening of the sealed Tarascan tomb found by the young friends. Leora's cousin, Ashley, joins Nicolas in his own archeological dig in the Hidden Valley as his parents, famous archeologists, prepare the tomb's opening. Young Luis begins to learn to ride on the wily pony, Payaso. The adults plan the training of the horses where all the young people are given jobs and horses. The growing excitement over the opening of the tomb spreads and the date of the opening becomes a worldwide event. Abuelita and a French chief plan a banquet for over a thousand people using the ancient recipes from the old hacienda. The event exceeds their wildest expectations. Leora, Juanita, Pedro, and Rafael compete in their first jumping meet. After the excitement, the young riders are invited to march in the Ciudad JuA rez 16th of September parade and to visit Mariana and Nicolas' grandfather's ranch in Santa Fe, New Mexico. Pedro and Juanita are filled with excitement; they have never flown and have never visited the United States! While at the ranch, the young friends discover the clues to the last great secret of Hacienda Palo Alto. While showing their great aunt Elena the changes made in rebuilding the old ruins, the elderly lady points out to recently engaged Elena and Carlos an important part of the building that had remained hidden ever since she left it at 15 during the Mexican Revolution. The young couple, along with Juanita's Cousin Jorge and the village schoolteacher; wed at the hacienda decorated in its ancient glory with the young Palo Alto frien