I picked this up the other day and thought I'd give it a try, never having read any of this series before. It turned out to be an ultra-violent western with a rape, shootings, fights, gun battles, beatings, torture, and just about anything else you can think of.
The Buffalo Hunter's name is O'Brien, and he's arrested and brutally beaten for a crime he didn't commit. He's sent to Bradenville, Texas' toughest prison, where the prisoners work in a big copper mine. The warden and the guards are brutal, and so are the prisoners. O'Brien's idea is to escape and get revenge on the men who really committed the crime he's accused of, along with the sheriff who sent him to prison. As you've probably guessed, he does.
That's it for the story, and I'll have to give Hayes credit. This is one book in which the action truly never stops. You're never more than a page or two away from another gunfight, beating, knifing, whatever, all described in loving detail. However, no buffalo are harmed.