I don't usually read thrillers, but I have enjoyed this one. I mainly loved the descriptions of the wilderness. 

I haven't read the first book in the series, but I could follow the story just fine. The only thing is that it kept referring to a past love, and where I could understand the impact that it had on Frankie, I did't feel the impact. 
Another flaw is that I wished that I would have loved the characters more. I feel like it would increase the stakes and make it more thrilling. A grumpy old dad and a few members from dudeville? No offence, but I don't care much if you stay alive or not. (Don't get me wrong, there were a few others I did care for, mainly because they where friendly towards Frankie. (and Daisy ofc, as she's the best dog))