Garth Nix and Sean Williams first collaborated on the Troubletwisters series, which they followed with a book in the Spirit Animals series, Blood Ties. Garth is also the bestselling author of the Seventh Tower series, the Keys to the Kingdom series, the Old Kingdom series, and Frogkisser! Sean's bestselling novels include those in the Twinmaker series and several in the Star Wars universe. Both Garth and Sean live in Australia - Garth in Sydney and Sean in Adelaide. This is their first book featuring Odo, Eleanor, and Biter... but it won't be their last.