Trouble, on a large scale, is brewing out in Montana Territory. Indians, settlers, trappers and frontiersmen fear to cross the ancient Old North Trail. No traffic is arriving from the west on the Mullen Wagon Road. War parties, wagon trains and mountain men who dared to trespass have vanished. Fort Benton is chock-full of folks who believe the rumours of 'Bad Medicine'. Many of these hardy adventurers have already caught a riverboat back to civilization.
A petition demanding an investigation has reached the White House. Preston Diamond has been assigned the task of either discovering or dispelling the source of the outlandish tales. President Ulysses Grant's rather vague “somewhere near the headwaters of the Missouri” doesn't give Diamond a whole lot to go on.
Bad medicine, bad whiskey and a hatful of bad hombres await his arrival.