The Violet Keystone
The Violet Keystone is the sixth and last book in Garth Nix's The Seventh Tower series , published in 2001 by Scholastic . 
<triplet> The Violet Keystone <subj> Garth Nix <obj> author <subj> The Seventh Tower <obj> part of the series <subj> Scholastic <obj> publisher <triplet> The Seventh Tower <subj> Garth Nix <obj> author