A stagecoach carrying a fortune in gold was held up at gunpoint south of Deadwood, South Dakota, in 1876. The mastermind of the crime made off with more than $1 million then quickly disappeared like smoke in the wind. The gold has never been found. The Hansen kids, while vacationing in South Dakota, stumble across a cave and some artifacts that might lead them to discover the truth about this mystery and recover a fortune in lost gold. But what they encounter during their quest is far more than a simple treasure hunt. They find themselves in a desperate struggle with modern-day armed bandits that threaten the lives of the children and their parents! It is up to Hannah, TJ, Noah, and Eli to save their parents and bring the bandits to justice.