The Killing Floor is a sequel to DiLouie's The Infection, a novel about a zombie apocalypse. However, these aren't standard zombies, as some mutate (or infect others to mutate) into strange monsters. It's zombie meets The Mist (by Stephen King). In the first book we follow a group of survivors living and fighting in a military personnel carrier in the vicinty of Pittsburgh. This book picks up right where the other book ends and keeps the action moving along at a fast pace.
The characters from the previous novels (those who survived) are here again, as are several new characters. The action no longer focuses on a single group, as it jumps around following the scattered survivors as well as the new characters. Ultimately, they all come together towards a climax involving a new type of infected monster. I won't give the details away, but suffice to say this new monster has the potential to win or lose the war for humanity. We do get more details about the cause of the plague, or at least its origins. The new monster is also heavily featured, so we get a sense of what it's like to be infected.
Overall, the action is fast and the body count is high enough to keep your interest and the tension high. I am only giving this book four stars because I felt like the ending (the last few pages) was rather forced. Again, I don't want to give away spoilers, but the reaction of the military at the end made no sense. Perhaps it was done to highlight the random futility of some efforts I suppose, but it was just poor writing in my opinion. But other than that, this book is a strong sequel to the original. The characters are interesting and complex for a horror/action book, the enemies are real and deadly, the apocalypse unfolds plausibly, and the book moves along at a good pace. If you liked the first book in the series, I'm very confident that you would like this sequel. If you are new to the series, I highly recommend starting with the first book, Infection. This book can be read and enjoyed on its own, but I don't think you'd get nearly as much enjoyment out of it as you would. As with any good zombie book, it's the characters that make or break the book, so it makes sense to follow them from the start. It's a fast, frantic, and sometimes horrific ride, but it's a fun one to follow. A solid four stars for sure.