Garth Nix & Sean Williams 
Troubletwisters 4: Missing Presumed Evil 

Page-turning adventures for fans of Percy Jackson and Harry Potter.Jack and Jaide Shield finally learn what it really means to be a warden in training as they pit their wits and their gifts against a rival – who is also a troubletwister!But as they explore the forbidden dark of the Evil dimension, they also have to come to terms with the truth about Grandma X’s twin sister and face their greatest challenge ever …