After stumbling upon the secret society of ninja librarians who transcend time and space, Dorrie and her brother have officially become apprentices. They are determined to help the Lybrarians find a missing key that could destroy their beloved fortress, Petrarch's Library.
- ISBN10 1402287739
- ISBN13 9781402287732
- Publish Date 7 June 2016 (first published 1 January 2014)
- Publish Status Active
- Out of Print 29 June 2021
- Publish Country US
- Imprint Sourcebooks, Inc
- Format Hardcover
- Pages 400
- Language English