The Prairie Rat - Black Horse Western Author:John Dyson In the town of Deadwood, Emerald O'Sullivan opens a bawdy house, but is torn between her desire for the prairie drifter, Amos Halo, and the staid Captain Thaddeus Birch, of the 3rd Cavalry. Amos joins Thad's regiment, but is soon sent out into the sub-zero Big Horns on a suicide mission.