The Black Dakotas.

During the Civil War, President Abraham Lincoln sends an emissary with a peace treaty to the Sioux Indians. He also sends a gift of $130,000 in gold. This attracts the attention of Brock Marsh, the secret leader of a Confederate spy ring, who wants to keep the treaty from being signed and to also get his hands on the gold. Ruth Lawrence and Mike Daugherty work together against the machinations of Marsh