When an entire family is murdered near the small town of Alva, Kansas, two things strike Deputy U.S. Marshal Jack Slade: first, that he'll be riding out to Alva in the morning, and second, that there was no apparent motive for the crime. In a town with no government of its own, that makes it all the more difficult to find the man—or men—who did it.
He calls himself the Prophet, and the word he brings is death. Sending his faithful followers to execute his chosen list of sinners, he claims to be doing the work of the Lord. But when his Avenging Angels call down the wrath of Jack Slade, it becomes the Prophet's word against the word of the law. And Slade does his preaching with bullets.