I'd read the The Forest of Hands and Teeth and The Dead-Tossed Waves about two years ago, so I was a little worried about reading The Dark and Hollow Places so much later. However, after a quick google search and some summaries read, I was able to dive right in. In actuality, I don't know how much I really needed to review the first two novels in the series. While characters in The Dark and Hollow Places did appear in The Dead Tossed Waves, this novel acted very much like a stand-alone. You didn't need the first two to understand it, in the same way it wasn't necessary to read The Forest of Hands and Teeth in order to understand The Dead Tossed Waves. 
 Moving on, I believe that while The Dark and Hollow Places is a post-apocalyptic zombie novel, it was more a story of love and self-acceptance. There wasn't a lot of action in it (except for the occasional running from zombies stuff), but that wasn't necessarily a bad thing. I actually enjoyed it, as I've been reading more "romance" novels for the past few weeks. The story focuses on Annah and Catcher, two characters who are on the brink of losing hope in the world. Catcher was introduced in The Dead Tossed Waves, as being a rare Immune, someone who is not affected by the zombie (or Unconsecrated or Mudo or... plague rat) "virus." Annah is the twin sister of Gabry. Annah blames herself for leaving Gabry behind in the Forest and has been permanently scarred by barbed wire, two things which seriously affect her self-image. It's kind of a typical story of two-"broken"-people-meet-and-fall-in-love, but it's honestly very sweet. Annah and Catcher find in each other the will to not just go through the motion of life, but to truly live without regrets, and it was nice reading their progress. Sometimes it did get a little slow, since as I said there's not a lot of action in this novel. But once I shifted my idea of the book being a zombie-adventure to being a story about love and healing, I enjoyed it a lot more.