A copy of the book: Percy Jackson and the Olympians- The Lightning Thief 

Percy Jackson and the Olympians is a very popular series. The writing is age appropriate for children within ages 10+ but can be good for mature readers. Content warnings (potential spoilers) for the first book includes: 
Mild fighting violence- demigods (children of gods: half-mortal, half- immortal) learn how to fight Greek monsters who attack and try to kill them. 
Death- Greek monsters are shown to die by turning into dust. Percy slices off the head of Medusa. 
Injury- Percy and his friends sometimes sustain injuries as they fight. 
Bullying- One character bullies Percy while he's at camp.
Child neglect- Some of the characters have backgrounds where they come from hard family backgrounds due to one parent being a God and absent in family life.
Lotus Casino- Percy and his friends get trapped in a hotel casino that makes them believe they want to stay there forever. 
Greek Mythology- References to Greek myths and the incorporation of the Greek Gods in the world is explained but does not give negative to any other religion. Percy travels to the Underworld. Discussion and comparison of original Greek myths may be talked about in class if necessary.