Relatively light-hearted book (in comparison with book 3), with a good plot and unveiling of some clues that were given in book 1. Yun Ge went through a round of near-death, but found her Ling Gege. After some initial misunderstandings, they were both happy for quite a few chapters, until suddenly Liu Fo Ling fell sick and started to push her away. At this point, you would think that she will discover it/Meng Jue will alert her to it and she will realise her foolishness.
So yes she does discover it, spent some time trying to battle the illness and surprisingly Liu Fo Ling recovered! (but nope, be patient, a few more chapters later he will fall sick again and die by the end of the book)
The author is really good at weaving in things that will be revealed in a later book, and you will be smacking yourself for not guessing it. And yet your attention is kept on the book such that you want to just finish the book and not put it down. It was so good that even I was amazed at my reading speed. I haven't finish a book in a single day (somemore it's a work day) since I started work.