As Tanner, Gwen, and their Beasts Firepos and Gulkien continue their search for the pieces of the Mask of Death, they face betrayal from Gwen's twin brother Geffen, and discover a new Beast-Rider pair--Castor and Nera.
- ISBN10 0545361583
- ISBN13 9780545361583
- Publish Date 1 June 2012 (first published 7 October 2010)
- Publish Status Out of Stock
- Publish Country US
- Publisher Scholastic
- Imprint Scholastic Press
- Format Hardcover
- Pages 176
- Language English