Imagine a novel about two best friends in an all-girl high school. In this novel, the protagonist learns an agonizing lesson about true friendship, and she falls in love for the first time but is unable to tell the boy the truth about herself. There are juicy universal teen themes in the book, and it’s wonderfully written. NOW imagine that same story of friendship set in an all-girl school for spies, where each girl speaks 14 languages and knows 7 different ways to kill a man, and the protagonist’s love interest is an “ordinary” boy who thinks she is just an “ordinary” girl. This book has juicy universal teen themes and is wonderfully written, but the spy school adds a distinct, easily articulated concept that pops it out of the pack in a big way. That’s the difference between a “quiet” book and a “high concept” book. The book? Ally Carter’s fab I’d Tell You I Love You, But Then I’d Have to Kill You, from the Gallagher Girls series.