In the 63rd of the series based on the Clarence E. Mulford character, Hopalong Cassidy is working on a counterfeiting case for the government and, with his two pals California Carlson and Lucky Jenkins, enters a town where they meet Nora Murray and her brother Sid, who have come to claim the "Silver Belle" mine. The brother is killed by the gang led by Ora Mordigan, and Cassidy discovers a lost mine where the gang has been holding John Murray, Nora's father, a prisoner and forcing him to print the bogus money.