This book is stunning. It's a WWII historical adventure about a pilot and a spy, both girls, told in the first half by the spy as a written confession to the Gestapo, and in the second half as a first-person narrative by the pilot. But it's also a puzzle, the kind of story where once it starts to unwind you realize that it's not what you thought it was. (and that's already probably too much information about it.)

What is especially notable about this book -- and its kind of sad that it is notable -- is that nearly all the characters are women, all of them are very real people, with histories and backgrounds and real flaws. There is no romance at all in this book. This is an adventure story about best friends, and it's one of the best books I've read this year.