The Book of Speculation

It's okay. Just okay. The flashbacks to the carnival are the best sections, for a LOT of reasons, the biggest one being that MOST of the characters in those sections are likable. The main character in the present-day plot unfortunately is not, and neither is his sister that he's so worried about. The big twist of the book (That the curse isn't affecting women in his family, but anyone who takes on the "mermaid" carnival role, meaning it can affect male water performers as well, and Simon becomes the curse target once he joins his sister's troupe) is guessable when you're about 1/3 of the way through. So after that point, the mystery becomes “how do all the pieces fit together?”

The carnival flashbacks were a lot of fun, though, and enough to make me say this is just “okay.” But if you want a mystery to keep you guessing, this is not it.