Ages 10 to 14 years

As a Ninja Librarian apprentice, Dorrie has the power to save Petrarch's Library—or destroy it. Now in paperback!
As an apprentice in the Lybrariad, a secret society of ninja librarians who transcend time and space, Dorrie must find the missing key that could destroy their fortress. She just has to get close to a lord with a connection to the Lybrarians' enemy—the Stronghold. But one wrong move could lead the Strongholders right to the very place she's trying to save…