4, The Shifting SandsBook - 2012
On his sixteenth birthday, Lief and his companions must venture into the darkest and most terrible places in all of Deltora to find the seven magical gems stolen from the Belt of Deltora. When reunited in the Belt, these gems-an amethyst, a topaz, a diamond, a ruby, an opal, a lapis lazuli, and an emerald-will empower the heir to the throne of Deltora and free the people from the evil tyranny of the Shadow Lord.
They have found three gems. Now they must seek the fourth, hidden on a shimmering, barren waste, kept jealously by an unknown guardian. Separation, confusion, and strange, terrible enemies await Lief, Barda, and Jasmine in the harsh landcape of the Shifting Sands.