A well written thriller for the younger boots and saddle circuit details Christopher's eventful summer as he goes from St. Louis to visit his cousin Melinda, whose father is an Atomic Energy Commission geologist working near Silverhorn, Colorado. An active girl, Melinda has prepared Christopher well in advance for what he will find- a mysteriously boarded up old house at Ding-Dong gulch. Detecting with Bucky, another cousin, and their friend, Whiz Daily, the kids uncover the past of Mr. Pengilly, who owns the old house. Hounded by a crook, Mr. Pengilly is mining in secret and when the crook is caught, uranium is discovered on the Pengilly property. Melodramatic, perhaps, but the suspense and fun are clean cut.