1919 on the high prairie, and a small army of people and machines moves across the land, bringing in the wheat harvest. Custom threshers, steam engineers, bindlestiffs, cooks, camp followers, and hobos join the tide. The threshing season is on.

But there is also an evil upon the land. A killer who calls himself the Windmill Man believes he has a holy calling to water the newly plucked earth with blood. The moving harvest is an endless supply of victims. He's been killing for years and has no plans to stop. Who could stop him? Nobody knows he exists.

But then a young man named Charlie Krueger, jilted by his childhood sweetheart and estranged from his drunkard father, joins the harvest as a steam engineer. But in a newly harvested field in the nearly black Dakota night, he comes upon a strange man digging a grave. Now he is the only person who can stop the evil. But the killer knows his name and when next they meet, one of them will have to die….