The Mark of Athena is by Rick Riordan. The third book in the Heroes of Olympus series. Percy, Annabeth, Jason, and the other four demigods head off on their quest to stop Gaea from rising. This quest takes them across the country and over the ocean to Rome where they must rescue Nico, who alone can tell them the location of the Doors of Death, and find the lost statue of Athena stolen millennia ago by the Romans. The cliffhanger ending to this book will ignite interest in the next volume for sure.
Ratings: 7th grade - 7 out of 10 - V (Violence).