The third book is a nice continuation of the Spiderwick series. In this book, the plot really starts moving and the Grace children uncover some very important clues.
The one thing I didn't like in this book was the chapter dedicated to the children visiting Lucinda in the hospital/asylum. The descriptions of residents in the hospital were a little dehumanizing by only focusing on their 'madness'. It seemed like a cheap attempt at making the whole situation seem scary, when really the residents are just people and should be viewed as such. Even the fact that Jared still views Lucinda as 'not sane' is a little irksome given that he knows everything she believes is actually true. I don't like that there is a character who is considered 'crazy' for the purpose of the plot (especially since we know she's right). This is especially problematic given that the terms 'mad' and 'crazy' are thrown about in such a flippant manner that it seems normalized and excusable. Given that this is a children's book written in the 21st century, I think there are more appropriate ways to incorporate mental health into literature. This is still a good work, but I wish the language had been chosen with a little more care.
Besides that, this is a very good installment. I cannot wait to finish the series.