The Sister of the South (Dragons of Deltora #4)

With the aid of Deltora's last dragons, Lief, Barda, and Jasmine have destroyed three of the Four Sisters, evil Shadow Lord creations that are poisoning their land. Their quest will end in the city of Del, where the Sister of the South lies hidden. Del is Lief, Barda, and Jasmine's home, but it has changed while they have been gone. Fear now stalks the streets, treachery lurks behind smiling faces, and evil prowls the palace. Even as they confront their own fears, the tree companions know they cannot turn back. For in the Shadowlands, the Shadow Lord gloats, waiting for the terrifying end.