I bought the book series on sale so I decided to just drive through all of it.
The dialogue reminded me of the 1950’s Western movie “Injun” talk. The author supposes that a couple centuries after a nuclear holocaust (I assume) that people will forget much of their language and revert to some kind of advance Tonto-speak. Implausible.
The premise of the story wasn’t bad, but it weakly assembled. There should have been more hints about how did the history develop. Such as, how did the cannibals living underground get there? Why would North Carolina and Virginia develop such catastrophic seismic activity that impassible fissures would open during sudden earthquakes?
Just pass on this one.