This book is the third in the author’s Miss Peregrine’s Peculiar Children books (after Miss Peregrine’s School for Peculiar Children and Hollow City). It nicely ties up most of the loose ends from the first two books, and I literally could not put it down.
The book begins with Miss Peregrine (a ymbryne, who by definition can assume bird form, create time loops, and manipulate time) captured by the evil Wights (led by her own brother Caul), and with nearly all the Peculiar children in her School having been herded onto a train in 1940s London by the Wights. Our narrator, 16 year old Jacob Portman, is in a call booth in the London station with Emma, a 15 year old Peculiar (born in 1901) who can create fire with her hands, and Addison, a Peculiar talking dog. They are trapped by a hollowgast, an invisible monster whose basic instinct is to eat Peculiars. However, Jacob discovered in the first book in the series that he is actually a Peculiar who can see hollowgasts, and in the second book he found that he can more or less communicate with them (with emphasis on the ‘less’ part, as he has no idea how how does it).
All that Jacob, Emma, and Addison need to do now is to not be eaten by any hollowgasts, evade the Wights who are actively searching for them, find and rescue Miss Peregrine and the other missing ymbrynes (all taken by the Wights), and their Peculiar Children friends before being out of their home Time Loop causes them to age quickly to their true age. Also, they hope to stymie Caul’s plans for domination of Peculiardom and of the world.
Readers would do best to have read the first two books in the series before reading this one; I also note that, due to at least two loose ends not being wrapped up by the end of the book, it would not surprise me if the author publishes a fourth book in the series.