This is a self-published, young-adult, sci-fi/fantasy/pre-apocalyptic/dystopian novel. There's so much going on that it's quite difficult to pin the book down to just one genre.
Don't let the self-published bit put you off, this whole book is treated very professionally, from the cover all the way through, with excellent editing and formatting. I know book reviews are supposed to be about the actual content of the book, but so many self-published authors completely overlook this, and it's a huge turn-off.
Naturally, the company which conducted the research and experiments on Michaela and her sister Nicole can't allow them to run free, and have to hunt them down.
There's something about Kayla that sets her apart from the rest, even from her sister. Those who owned the compound where the girls were kept are especially eager to find Kayla, but she has no idea why.
The mix and contrast between tough girls trained and bred to fight and kill, and young naive teenagers is perfectly balanced and realistic. You never feel the characters are unbelievable in their actions, whether they're beating the hell out of the monsters that escaped with them, or desperately seeking ice cream.
The pacing of this book is perfect. The action scenes (of which there are many) don't fly by in a blur, nor do they get dragged out in slow-motion so the author can fit in all the details. It's like reading in realtime.
This book ends on quite the cliffhanger, I can't imagine how anyone could read it and not instantly want the second book. The book raises a helluva lot of questions about the girls and their origins and the company behind the Sphinx project, and so much more. It's an excellent set-up for what should be a fabulous series. (In her interview on this blog, Kate said there's at least two more books to come!)
There's just a hint of romance in the book, and I loved it. It's subtle and it's as though neither of the characters involved realise there's a romance brewing, which is my favourite part of any romance story.
It's a great fast-paced, action-packed YA read, but you definitely don't have to be YA to enjoy it. I loved it, and I very rarely read any YA.
Oh did I mention it has zombies?