Chapter 40 is where we first meet the Gnomes, and their leader Carmenaren. Once Talstaff has been returned to the surface, the following chapters, chapters 41, 42, 43, 44, and 45 all cover our adventures with the first of the two Troll tribes - the little test that she wanted dealt with to prove our worth. Chapter 46 covers the fight with the Troll Shaman, the leader of one of the tribes, and chapter 47 is our return to the Gnomes, and then the return to the surface.
Chapter 48 covers our subsequent return to the gnomes from a short trip to Milbourne, and they tell us that only one Troll tribe remain, and the fight begins in this chapter. It continues in chapter 49, where we kill the last of them, and in chapter 50 we get the above map and information on each of the sections, and to further our quest by explaining that the illithids are behind the kidnappings. The Diregund, or 'evil mostachioed dwarves' are also brought into the tale, and Carmenaren tells us that they are our next target.
Chapter 63 details the start of our (many) travels back to the surface, and contains many more fights - mostly Giant orientated, and we finally get back to the Gnome area, although I am sure they will not continue to welcome us if LotD continues his special 'interest' in using Gnomes for his latest experiments.