amazing book I loved it !!
before reading this book you should read the other two !
• this is a non spoiler review
there are 7 main characters : Jason/Percy/Piper/Leo/Frank/Hazel/Annabeth
side characters (but still important ) : Couch Hedge/Nico Di Angelo/Reyna/Octavian/Dionysus/Hercules...(can't remember the others )

I can't really review it without spoiling the book 1 and 2 but in the end when I finished the last Chapter I was alone at home and for a hole 8 minutes I was digesting what i just read I was literally shocked and impatient to buy the 4th book : the house of Hades