 Two escaped convicts break into a trapper s cabin. While the man is sleeping, they eat his food, steal his pelts and a rifle and leave. What they don t know, however, is that the trapper wasn t sleeping--he was dying of smallpox. When the Rangees discover what has happened, they set out to capture the fleeing men before they re able to get to Portsmouth and bring that contagious, and fatal, disease with them.