Question: The Battle of the Labyrinth is the fourth novel in a pentalogy of adventure and mythological fiction books that have sold more than 45 million copies, and have been sold in how many countries?
Sentence (from "The Battle of the Labyrinth"): Percy Jackson, a fictional demigod (who is fifteen years old by the end of the book) attempts to stop Luke Castellan and his army from invading Camp Half-Blood through Daedalus's labyrinth by trying to convince the inventor not to give Ariadne's string to Luke.
Relevant evidence: No