What this book is about (assuming you have read Miss Peregrine's Home for Peculiar Children): 
 Shortly after the Peculiar Children, Jacob and Miss Peregrine, injured and in bird-form unable to turn human, escape from the island and time starts running again, they find themselves in small boats in the sea. Their main goal is to make it somewhere safe and to survive. To do that, they have to find a way to turn miss P. back to her human form so she can take care of them. Hollow City is about the groups adventures while trying to find a way to turn miss Peregrine into a human again while time is running out. If they don't make it soon, she will stay a bird forever! 
 Hollow City reminded me a lot of the Series of Unfortunate Events by Lemony Snicket which I really liked when I was a kid. As an older "kid" now however, I felt that this book tired me out. For the most part of the book it was as if events were happening in a circle over and over again. I got a little bored and was not very excited about the ending which is probably the best and most twisty part of the book. 
 "Strange, I thought, how you can be living your dreams and your nightmares at the very same time." 
 But enough of what my adult self thinks of this book. I am very confident that this is a brilliant book for young readers. I wouldn't call it YA literature even though the protagonist, Jacob is 16 (or 17?) years old. Many of the characters are children and the dialogues are quite simple. More like a Middle Grade book, in my opinion. So I will try my best to treat it as a Middle Grade book. 
 "Do you ever find yourself climbing into an open grave during a bombing raid and wish you'd just stayed in bed?" 
 If Miss Peregrine and the children's story was published when I was in school, I would have devoured this book for sure and it would have become one of my all time favourites. There is a lot of action, there are lovely characters, hilarious conversations and a magical atmosphere. Another plus is that it shows children some history about WWII which doesn't exist in many time-traveling, Middle Grade, fantasy books. And to make history exciting and interesting..that's another big accomplishment on itself. Another thing I don't want to forget to mention is that there are more pictures in the book than in Miss Peregrine's Home for Peculiar Children and they are breathtaking. They add to the whole creepy, mysterious atmosphere surrounding the story and bring it to another level. 
 "That's because the true purpose of money is to manipulate others and make them feel lesser than you." 
 "I'm not entirely sure about that," Emma said. 
 "Only kidding!" said Horace. "It's to buy clothes, of course." 
 I did feel that Hollow City dragged out in the beginning but the end is fast-paced, full of action and unexpected, interesting twists! For me, it's always a plus when a book has a powerful ending and this one did not disappoint. I would strongly recommend it to anyone who enjoys Middle Grade books and to all young readers.