Wow, I really loved this book. Such a great idea, a sort of Sliding Doors but for gender. The book follows the lives of one person Lou Alder, but splits into two timelines where they are female and in the other male. Both stories are fascinating and would stand up in their own right, but the real joy is in seeing how they intersect. The similarities between the two are intricately plotted, and even the vast differences seem to come back to the same thing in the end.