I've seen this movie subject done at least a few times before. Yet, I haven't taken the time to read this particular setup in a book, so it was something I was excited to try.For the most part, Secret Sister was executed well. You have two best friends who get into a car accident. One dies (not a spoiler, this happens at the very beginning), and one lives. The reader learns right away from the book synopsis that not everything is as it seems. However, we don't get to see this while reading the book until close to the halfway mark. I failed to understand the need to "wait" for Cathy to find out who she is, when we all know before picking up the book what's going to happen.It's like Freaky Friday, except one person kicks the bucket. Hah. The story itself had me. I was anxiously awaiting the moment when Cathy would figure out that she was Cathy, and not Roxanne. And I really wanted to speed ahead to the moment when Cathy's husband figured out who she was because I wanted to know how he would react.Even though the story was working for me, I struggled with the characters. The real (deceased) Roxanne (who we find about through everyone else's accounts) seemed like a shallow and uninteresting person. Plus, it didn't help that Cathy was way too forgiving when she found out about how badly people had done her wrong. This 'quick to forgive' attitude made me turn sour toward her. When she thought her husband had participated in an affair; she was ready to jump back into bed with him right away???. It also didn't help that Cathy participated in behavior herself which seemed out of character for the type of person who she was being portrayed as. I got tired of all the deceptions and lies. And we won't even go into the complete pointlessness of Roxanne's ex-boyfriend as a character. How do you root for characters when you don't like them? This was the hard part for me. I wanted to know what would happen next because with an extreme story such as this one, the curiosity to want to know how it's all going to turn out overrides everything, even one's dislike of the characters.This leads me to wonder how I felt about the book in the end. I did actually find myself absorbed in the storytelling and I couldn't turn the pages fast enough, which is a good thing. Would I recommend the book? Possibly. If you haven't watched any "body-swapping" or "body invading" movies, I'd say you might want to give Secret Sister a shot. It's a freaky concept and one that is probably worth the experience at least once. If you have already watched a few movies featuring this subject like I have, I'd say that you might not find anything new here to get excited about.This book provided from the publisher through Netgalley in exchange for an honest review.