I loved this story. I was thrilled to see another book from Ally Condie because I loved the Matched trilogy. This book is a stand-alone novel which really nicely melds together the concepts of sirens, an underwater city, and a dystopian world. I expected this to be the first in a series (most likely a trilogy because everything is a trilogy these days) but it is a stand alone. Which I'm very ok with because while I like having multiple books for a story and characters I really like, I always get exhausted by the third book. I thought the story worked out well for one book. If it does strike Condie's fancy, there is enough information given to us in this book to make more books from. The book starts out with the quintessential dystopian ceremony. In Atlantia, when the youth reach a certain age, they choose to stay below in Atlantia or to go Above and live a life of sacrifice in a now deadly polluted world, working to keep Atlantia running. Rio has always wanted to go Above but since the death of their mother, Rio has promised her twin, Bay, that she will stay below so that they will still be together because there always has to be one member of each family in Atlantia. At this point I figured the book would be about how Rio stays Below with Bay but is regretting her decision so she tries to get above. Nope. I was hit with a major and shocking plot twist a few pages in. Rio chooses to stay in Atlantia as she promised Bay, but then Bay chooses to go Above. Rio is very upset because not only did her sister leave her, but now Rio is stuck below and must continue hiding the secret that she felt she wouldn't have to hide if she went above. Rio is a siren, just like her aunt Maire (I hated that name. I never knew how to pronounce it as I was reading). In Atlantia it is dangerous to be a siren. The Council has lead to believe the citizens that sirens are dangerous and the Council uses sirens for their own purposes. Being a siren is even more dangerous for Rio because there has never been more than one siren in a family. Rio needs to get Above to be with her sister and turns to her aunt and True, the best friend of a boy who left with Bay, for help. While figuring out a way to get above she learns about who she is, who her family is, and what Atlantia really is, and the answers will surprise you. I definitely recommend this book. I thought it was a great story. I can't wait for what Condie writes next because so far everything she's written has been great. 
 Thanks to Penguin First Reads for the ARC.