Exciting Yet Darker Than Previous Books
In this book Percy and some of his friends venture into the labyrinth: a maze that's alive and designed to kill. Some of the places Percy arrive at while he struggles through the labyrinth have mythological monsters or less than kind humanoids. One character, who seeks revenge on Percy, conspires with a ghost who tried to betray him. Said character (alright, alright its Nico) also raises the dead in attempts to communicate with his deceased sister. He later calls himself the "Ghost King", though by the end of the book he no longer wants revenge.
Also a side note, yes this is a popular series. You can find many things related to this series on the Internet that are fan made. Some bad, some good. Yes this series is a "fandom" with a large following of "fangirls". (Both of those are 21st century terms you may or may not be familiar with.)
This title contains:
Positive role models
Violence & scariness