The summer of 1919 is over, and on the high prairie, a small army of men, women, and machines moves across the land, bringing in the wheat harvest. Custom threshers, steam engineers, bindlestiffs, cooks, camp followers, and hobos join the tide. Big Wheat is king as people gleefully embrace the gospels of progress and greed.

But with Big Wheat comes a serial killer who calls himself the Windmill Man. He believes he has a holy calling to water the newly plucked earth with blood. The mobile harvest provides an endless supply of ready victims. He has been killing for years now and intends to kill for many more.

A young man named Charlie Krueger also follows the harvest. Jilted by his childhood sweetheart and estranged from his drunkard father, he hopes to find a new life as a steam engineer. But in a newly harvested field in the nearly black Dakota night, he has come upon a strange man digging a grave. And in that moment, Charlie becomes the only person who has seen the face of a killer....