After recovering the governor of Montana's famous dog, Cat, in "The Governor's Dog is Missing," twelve-year-old sleuths Slate Stephens and Daphne McSweeney head to the infamous Montana ghost town of Bannack. While their geologist dads prospect for a large gold mining company, Slate and Daphne encounter a pair of perplexing puzzles. Under an old classroom desk in Montana's first schoolhouse, the young detectives discover clues pointing to missing gold treasure amassed by Montana's vigilantes 150 years
earlier. At the same time, a thief has absconded with two priceless Charles Russell paintings on loan to the university art museum in nearby Dillon.