The Kentuckian was sure of only one thing right now, he was not going to enter a town or a stretch of country where Hunt Rennie was the big man, and claim to be Rennie's unknown son.
The Kentuckian wanted to be in towns where Hunt Rennie was in charge.  
mnli hypothesis: The Kentuckian wanted to be in towns where Hunt Rennie was in charge.   premise: The Kentuckian was sure of only one thing right now, he was not going to enter a town or a stretch of country where Hunt Rennie was the big man, and claim to be Rennie's unknown son.