In August 1914, recently orphaned Cooper Harrison arrives in El Paso to live with grandparents she's never met. The minute the fifteen-year-old steps off the train, everything seems wrong. The heat is stifling, her grandfather Luther is cold and appraising and, worse, doesn't even mention the recent loss of both parents. Her grandmother, Angelica, is remote and childlike and wears only black and diamonds.
When Cooper asked to come live with her grandparents, she thought to help in the family antique business and soon shows her aptitude for the field. But, she soon discovers that Luther not only runs a "shady "concern but also profits from the Mexican Revolution smuggling arms across the border.
Luther leaves for Mexico with a wagonload of bullets hidden in sacks of corn and is kidnapped by Pancho Villa's men, and Cooper realizes she's the only one to carry the ransom to Villa's camp. She meets a Hollywood actor and cameraman--in El Paso to film Villa's life--and convinces them to join her in the attempt to rescue her grandfather. The ensuing adventure takes the reader on a wild ride deep into the Mexican countryside.