From the Introduction:
It’s 1862 and you’ve been hired to protect the construction of what will be the first transcontinental railroad. Like most of the middle states, Kansas still hasn’t recovered from the devastation caused by the Yosemite eruption before the turn of the century. No sane folk live between the soot of the sky and the ash of the earth, but you’re here now to see that the East gets access to the precious fruit and produce that grow west of the Rockies. The trouble is the folk who do live here.
In addition to the great famine, the air poisons the land and the water, emaciating and driving mad the humans and mammals exposed to it. People become so listless they might as well be dead. But they don’t die. No one understands it, but these diseased individuals go on, without memory, sense of self, or any civilization. They are called ‘husks’ and they are a pitiful nuisance at best, terrifyingly dangerous the rest of the time, attacking normal humans on sight, clawing and biting without regard for civility or their own safety.
Your job is to protect the rail workers as they lay the track west, and you do, but the railroad also asks you to clear out ghost towns that are in the way, to investigate worrisome occurrences, and to handle the locals however necessary. Your title is wrangler, but some call you railroader.