Presumably the last book of the Sisterhood of the Travelling Pants for reasons that will become apparent as one reads the book. The four girls realize that friendships take more work than just shipping a pair of pants around which is a lesson well learned. The book isn't quite as charming and innocent as the first three, but still well worth reading in order to tie knots on story lines. Besides, anybody who's read and enjoyed the first three will want to know 'what happens next' - including me :)