We start with the eight volumes of Deltora Quest. Then the three book Deltora Shadowlands series. Then the four volumes of the Dragons of Deltora.
This book is Volume 1 of the middle Deltora Shadowlands series. In the Quest series, each volume concerns a search for one of the gems that fits in the magic belt of Deltora. In the Dragons series, our heroes must find and destroy the Four Sisters, one per volume.
This series involves the rescue of hostages taken to the Shadowlands at the end of Deltora Quest. The three books cover the search for the three pieces of the Pirran Pipe.
Now, all of this sounds like the same book, over and over again. However, Rodda keeps each book fresh. She keeps an eye on the arc of each series, but gives each individual book its own appeal. That is quite a feat. But since this is the first book in the Shadowlands series we do also get all of the introductory setup before the adventure begins.
Unfortunately, there is a lot of wheel spinning before our heroes get on the road. There is also a sort of romantic sup-plot based on misunderstandings between Lief and Jasmine, and that is not a strong narrative thread.
So, if you're not inclined to go all the way with the Deltora stories, so far this middle group is the weakest link in the overall Deltora saga.
But that said, while Rodda's Rowan of Rin is for younger readers and is a great introduction to quest fantasy, these books are still a fine next step. Deeper characters, more complex plot, more demanding writing style. A wonderful introduction to quest fantasy and very accessible and very satisfying.