There's an extraordinary secret hidden just beneath Ruth Mason's feet. The year is 1905, and Ruth is a prairie girl living in South Dakota. She has no way of knowing that millions of years ago, her family farm was once home to scores of dinosaurs. Until one day, when Ruth starts finding clues to the past: strange rocks and rubble scattered all across her land. They're dinosaur fossils-but she doesn't know that yet, either. It will take many years of collecting these clues, and many, many questions, but Ruth's curiosity will one day help uncover thousands of fossils all across her land.