After rather striking adventures on Lake Superior and in the Florida Everglades the boys had been persuaded by Mr. Horton, a well-known criminal lawyer of Chicago, to undertake a mission in the interest of a client in whom he had become greatly interested. The lads had already arranged a vacation trip to the Great Divide, and it necessitated only a slight change in their program in order to make the investigation desired by the attorney, who had shown himself their friend on more than one occasion. In fact, the Superior trip had been taken at his expense.