After I initially finished ALL OUR YESTERDAYS, I realized something peculiar. The one thing I remembered more than anything – and mind you, this was within ten minutes of finishing the book – was the time travel system. ALL OUR YESTERDAYS is a book about two versions of one girl (16 year old Marina and I assume 20 year old Em) as they come to terms with the fact their friend James is a soon to be homicidal maniac. Well, it’s kind of like that. Em has tried 14 times so far with Finn, James’ other former best friend, to kill the Doctor (aka James age 22).I apologize if that’s a spoiler, but I thought it was pretty damn obvious from like page 10. I’ll just repost my time travel deconstruction so that you can see why this book has stuck with me, probably for the wrong reasons. More than the characters or the pacing or the plot itself (which were mostly good, but not without their flaws), I kept thinking about the time travel system in ALL OUR YESTERDAYS. You guys, I think this book itself is a paradox because the time travel aspects don't really make much sense. If you go back in time 15 times to kill various people before you die, then the paradox ends after that event. Therefore, those people would be dead when you then went back and killed another person, or created another event. Therefore, 15 events would have happened in one timeline, or else you're just creating a multitude of multiverses existing on parallel levels, which is a whole 'nother thing completely. They would have just created 15 different universes based on 15 different events, including a lot of murders of innocent people just like they were playing with ingredients in a failed recipe. The science does not account for how time goes back weeks after the paradox ends and that timeline is completed (apparently with Em and Finn 2.0 dead) to therefore erase everything that happened to create another timeline. So judging by the number of times different people went back, there would be several hundred if not thousand timelines, each with a tiny difference, but each would then be erased if another person went back in time. And it's not like they make a to do list for each time traveling hitman to complete everything, or else killing all these people would then not work. Also, even using the same science as seen in ALL OUR YESTERDAYS, the ending makes no sense. It wouldn't happen that way. But I'm not going to spoil that, but be prepared to roll your eyes at the convenience.Yeah, I’m having problems here, but let’s just deal with the rest of this very interesting debut science fiction thriller by Cristin Terrill, a book with a great deal of hype (it was a BEA Buzz Book) and for good reason.EVERYTHING BUT THE TIME TRAVELI’ll start with the pacing, which was pretty on point except for a few lulls. The story is quick, action-packed, and I finished it pretty damn fast once I got into the story. Admittedly, this took a while. I put the book down, got back to it, put it down again, and then finally returned for one last crack at it all. I finished the last 200 pages in one sitting. Beyond that, I just couldn’t with the characters. From their motivations to their character changes, it just didn’t seem to make much sense. Beyond that, Marina’s friends just plain pissed me off with their classism and complete disregard for humanity. But that was probably their intent. Whatever. Ignore that.Something about this book felt so right, but it felt so off. It was well-written, that was for sure, and the sheer imagination of some of the aspects blew me away. And it really was thrilling. I predicted parts of it, but it was exciting nevertheless. I enjoyed ALL OUR YESTERDAYS, and Terrill definitely has talent, but this book just was confusing, plain and simple, from the time travel to the characters to the fact they built a super collider in like…two years. Is that even possible? I highly doubt it.Oh, and to wrap this up quickly, I probably won’t read the sequel. This book was a perfect little wrapped up standalone, and unless the Terminator shows up and tells Marina, “Come with me if you want to hasta la vista,” I’m just going to pretend it was a standalone.VERDICT: Saddled with a time travel system that still confuses the crap out of me, ALL OUR YESTERDAYS is a book with an amazing, exciting premise. The problem is that maybe some of this just goes over my head, leaving me dwelling on what I shouldn’t, leaving the book a disappointment.This review brought to you by the girl who wanted to be an astrophysicist before they told her her math wasn't that good and said she'd make a good politician instead.