Rockspur Ranch, a small cattle industry located on the plains, had been left to Mrs. Wallace by her bachelor brother, George Rockford, and the Wallaces had come out, partly for the banker's health, but also to inspect the newly acquired property.
Frank Allen and Paul Bird had been asked to become members of the party, and Minnie Cuthbert, the prettiest and most sensible girl in all Columbia—at least so Frank was firmly convinced—was along to keep Mrs. Wallace company.
A man by the name of Nash Yesson had tried to buy the property from the new owner. That failing, he had, with the assistance of Lef Seller, known as the bully and worst boy in Columbia, tried to get possession of a treasure he knew to be buried in a cellar under the ranch pantry.
The vigilance of Frank Allen and his chums defeated this effort, and the plotters were chased off, leaving the old rusty iron box they had dug up in the possession of the rightful owners. All of these happenings have been narrated in the pages of the book just preceding this, under the title of "Frank Allen at Rockspur Ranch."
Lanky's uneasiness concerning the possible continued efforts of Yesson and Lef to steal the valuable paper and chart that, with gold nuggets, had lain in the iron box so many years, accounted for his suspicions that the mysterious nightly visits of the man with the big head were connected in some way with the long-buried treasure.
One of the papers yellowed by age that fell into the Wallaces' possession had been a rudely drawn chart of a mountainous section of country where years before gold had been found in paying quantities and a little mining settlement named Gold Fork was located.
It was understood that this place was now deserted, the shacks in ruins. So all hope of ever locating the long-lost mine worked in secret by Josh Kinney, former owner of Rockspur Ranch, died away.
This map had been drawn by Josh Kinney himself. Its existence was known, but no human eye had ever beheld it save the maker's up to the time it fell into the possession of Frank Allen and his two chums.
Jerry Brime knew something about the lost claim, for he had worked alongside Kinney at cattle raising and had himself tried, but without success, to follow the other when he disappeared. Jerry believed that Kinney was laying in a fresh stock of gold nuggets from the rich deposit, or "pocket," in his secret mine when this happened.
Brime and the three boys held many consultations as the days passed. The boys were bent on making an effort to locate Kinney's source of treasure-trove, and so asked a multitude of questions. Some of these Jerry answered readily, but in other cases his memory failed him.