Unforgiven — M.R. Forbes

Sheriff Hayden Duke was born on the starship Pilgrim, like his father, and his father before him. He's got a long way to go before he can rest. How can he when the entire world is under siege? By demonic aliens. By a brutal thug who calls himself King. By an unknown and powerful threat that may be responsible for the end of humankind. The road may be long. The odds may be bad. The stakes may be high. You can't keep a good Sheriff down.