Cliffhanger warning 
 Parallel universes are a tricky topic in fiction. I've read my share of them, and the majority have been fairly horrible. They tend to be poorly explained and in the end, I am left with more questions than the answers I was given. The failures stem from the lack of scientific backing, or rather the lack of make-believe-science backing. I can believe either, so long as the "evidence" for such a parallel universe presented makes sense to me, and in that sense, this book's parallel universe was very well described and explained. I had my reservations and I had plenty of questions...and all my concerns about the concept were addressed quite nicely. 
 The background was well executed, but the characters were considerably less enjoyable. I found no enjoyment in the characters; with the exception of one side character, I felt most of the major characters in the book were unlikeable, idiotic, and inconsistent in their behavior and thought. 
 16 year old Sasha Lawson is flabbergasted when her longtime crush Grant Davis suddenly asks her out to prom. After a lifetime of looking at him from a distance, of never having had his attention, of being solidly smart but under the radar at school, of resigning herself to the fact that her schoolgirl crush will never come to fruition, Grant suddenly asks her to be his date for Prom on the very same night he notices her for the first time. 
 Totally not suspicious at all. 
 The problem is that Grant isn't actually "Grant." "Grant" is actually the analog (read: double) of Thomas Mayhew, from the United Commonwealth of Columbia. A secret agent in an alternate universe. After prom, he kidnaps her, and they travel back to his world, where he needs Sasha to pretty much play a stunt double for the missing Princess Juliana. They have a deal, she is to play Juliana for a week, then Thomas will return her back to her world. Naturally, there are always complications, and Sasha finds herself falling for the boy who has kidnapped her, while trying to solve the mystery of her connection with Juliana and her whereabouts. Who is the person leaking information to the enemy Libertas? What is Juliana's real scheme? 
 The Setting: Quite well done. The world in which the United Commonwealth of Columbia is set in was identical to our version of Earth, if not for the Last Common Event taking place during the Revolutionary War. Then, the two worlds diverged, and therein lies the difference between the worlds. There were some details that remained unexplained, that bothered me somewhat, but overall, the history and the explanations behind the parallel worlds were adequately covered. I had a lot of questions about the worlds, and what I thought were inconsistencies, but they were eventually explained. 
 For example, it bothered me that Juliana and Sasha's parents were not the same people on their respective worlds. I mean, what the hell, right? There's such a thing as DNA...we are made from some very, very specific combination of DNA from both our respective parents, so how the fuck is it that Juliana and Sasha can be physically identical, each others' "analogs" not having come from the same parents? To my shock, that was actually addressed in the book. 
 "I still don't understand," I said. "What about DNA? If we look the same, shouldn't we come from the same parents?" 
 "Are you familiar with Anaximander's theory of apeiron?" Dr. Moss asked. I stared at him blankly. He sighed. "...As far as I can tell, that's what an analog is--a worldly fragment of one whole and perfect being that exists only in apeiron. 
 "Have you ever visited a hall of mirrors, Ms. Lawson?" I nodded. "Imagine standing in one, then. Everywhere you turn, there are multiple reflections of your own image. The mirrors are expertly arranged so that these reflections appear to multiply in every direction, stretching out into infinity. You look alike, you move in perfect harmony, but the reflections are not you. They simply have their origin in you. You are the primary being, and they are mere copies. That is an imperfect but adequate example of what I mean." 
 That's good enough for me! 
 The vocabulary involved with the concept of the parallel world and its people were well explained. An analog is the version of you in the parallel universe. The tandem is the veil that separates the worlds. The problems of analogs meeting, etc., all were exceptionally well explained compared to other books I've read regarding the subject. I have very few complaints when it comes to the world building. 
 (Although I'm still confused as to why the fuck there's an AURORA present in the sky of the other world when the two are supposed to be the same. And potatoes can't grow in the United Commonwealth? Come on, I can leave a potato in my pantry for a month without water nor soil and it'll start sprouting on its own. Give me a break.) 
 The characters: Fools. Sasha is not my ideal heroine. She is supposed to be really, really smart, but acts like a scared little girl. Understandable, given the fact that she was kidnapped and all, but the majority of the things that made her cry in the book were just completely stupid and I like for my female MCs to be more respectable and dignified than that. I would understand if Sasha sobs her heart out because she's terrified for her life, but she cries in response to idiotic, minor things, like finding out that Thomas lied to her about his mom. Because that's such an important event. Um, no. 
 She overreacts, she is inconsistent. She cries far too easily, far too often, and then turns around to too completely competent to be a believably flawed character. She gives a fucking TELEVISED interview within hours of becoming "Juliana," she rarely stumbles at all in fooling people into thinking she is the princess. I don't believe it one bit, and I don't find her a likeable or credible character. Sasha forgives Thomas far too easily for the crimes he has committed against her. It is completely unforgivable what he did to her. Thomas gained her trust, then betrayed it, he threatens her life, he endangers her life, and she develops feelings for him. No, thank you. 
 I couldn't figure out what it was about him that made me so angry, and at the same time melted my insides like butter left out to soften. 
 I can tell you what it is about him that makes you so angry, Sasha. HE FUCKING KIDNAPPED YOU. 
 Because no matter how hard I tried to make myself see reason, all the feelings I'd started to have for Thomas when I thought he was Grant just wouldn't go away. 
 Stupid, stupid, stupid. 
 Thomas is a fucking asshole. I'm sorry, there's just no other way to put it. He's manipulative, he is an idiot, and he is a prime example of nepotism. He is 18 year old. Pretty much an infant where law enforcement is concerned, hell, you can hardly find any police officers in our world who are under 20, but at the glorious age of 18, Thomas is a member of the very elite, very skilled King's Secret Service. It's equivalent to the President's Secret Service, and Thomas is the son of the very powerful, very influential General. Did I say nepotism? I mean nepotism. Skills, my ass. 
 Thomas "seduces and kidnap a sixteen-year-old girl," and then is completely astounded, SHOCKED, I tell you, when he sees that she's mad at him. He doesn't know why it takes her awhile (five minutes, tops, actually) to trust him after having pulled her into his world and demanding that she does whatever he says or never see her home world again. 
 He literally dangles her off a high rise in order to get Sasha to remember some crucial details. Because scaring the living shit out of a poor girl is the most effective way of getting the information you need from a girl you're slowing coming to love. 
 The level of stupidity is high with this one. Thomas and Sasha makes the perfect Stockholm Syndrome couple. He kidnaps her. She still likes him anyway. 
 Oh, and did I say there's a love triangle? There's a love triangle. Insta-love and a love triangle. Yay me! 
 The alternate character, Juliana, is similarly deplorable. She is a stupid, selfish, spoiled princess, who is too ready to throw away her future and the safety of her nation for the sake of escapism. It is fitting that she is Sasha's analog, and I can only thank the gods that we don't meet any more of their analogs, because I'd have a long list of naming and shaming all the ways I wanted to kick some sense into their silly addle-brained heads. 
 Read this for the interesting concept of an alternate universe, but don't expect much out of the characters. 
 This book was provided as an ARC by Netgalley. Quotes used were taken from an uncorrected galley and subject to change in the final edition