The furthering adventures of young Jacob and the island of misfit mutants. Not to be too spoilery, in the second book the peculiar children set off to find a ymbrne to help Miss Peregrine. On the way, they encounter more danger and a scary new threat that could destroy them all.
The major draw of this series for me is the pictures, all old black and white pictures. There are plenty of new ones in Hollow City, so I was satisfied (Even though a lot of them are landscapes and other establishing shots).
You can read my full review here. There are spoilers for the first book, so take caution.