All Our Yesterdays had one of those winning premises -- simple to grasp, yet filled with conflict, emotion, and fascinating philosophical questions. The story was also ingeniously plotted -- one of those books you can hardly put down.Em and Finn are prisoners in adjacent cells, tormented and tortured daily by captors who want to know the locations of secret documents. Marina is a carefree teenager in Washington DC, a girl in love with her next-door-neighbor. Em and Finn need to go back in time to try to stop a terrible chain of events that plunged the world into chaos. Marina is shocked and dismayed when a madman suddenly targets her neighbor's family.After reading only a chapter or two, it became very clear to me exactly what was going to happen in this book, and that only made the story more exciting. There was just enough science for me -- a brief explanation of how time travel paradoxes are resolved*** -- but not so much that the focus was taken off the characters and their conflicts.The moral dilemmas that these characters faced were really set this book apart for me. Action scenes without any kind of emotion behind them are exciting in the moment, but ultimately empty. All Our Yesterdays had action plus wrenching emotion, placing characters in conflict and raising interesting questions: could you take a human life if you knew that it would make the world a far better place? How far would you go to save someone you love? Whether or not you're a fan of time travel books, I think you'll appreciate the very clever plotting and absolutely excruciating tension that this book sets up. I highly recommend it!