This is the second book in the “Percy Jackson and the Olympians” series, where Percy must complete quests for the gods in order to get letters of recommendation for admission to New Rome University.
Funnily, he seems more focused on going to college to be with his girlfriend Annabeth than on actually going there to learn anything. You may wonder why someone who routinely saves the world is worried about getting into college. The back story is that Zeus does not like Percy, and so he has declared that he must complete three quests to gain admission to the University. This is one of the only schools for demigods.
For his second quest, which is also the funniest, he is employed by Hecate the goddess of magic, to pet sit her polecat Gale and her hellhound Hecuba. On the second day, both the pets run away from the house while Percy and Annabeth are in school. Through their quest to get these pets back and repair Hecate's destroyed house, Percy and Annabeth learn the stories of the pets, who used to be humans living in Ancient Greece.
What I really liked about the book is that it told the story of Hecuba, the Queen of Troy before Hecate transformed her into a Hellhound and the story of the magician Gale, who was rescued from a lifetime of not being able to practice magic by being turned into a polecat. I would recommend this book to people who have read and loved Percy Jackson. It is not necessary to have read the first book in this series to understand this one, but the reader should be familiar with the other Percy Jackson stories.