A really great book. First and last chapters are a warm and poetic and I simply love them - because they remember me about my younger self, reading this kind of novel, eons ago.
The rest of the story is different kind of joy: a clever crime plot (we're looking for a jewel thief) with lovable characters, on a train travel from Paris to Istanbul, with twists, a lazy police officer, and well a super cool nun.
Of course, this is a book for teenagers. But this doesn't mean it's not a nice experience even for older readers.