Chapter 6 introduces the city of Blingdenstone, home of svirfneblin.
It's a well written and complete chapter, which describes also many places just outside the city.
The place is a safe haven to have a rest, hide from the Drow pursuit and find useful clues to get out from the Underdark.
PCs will find many different side-quests as well.
Make the party get involved in as many side-quests as possible. The more they complete the more they will gain svirfneblin's trust. The deep gnomes know a lot about the ways leading to the surface world.
Even if it's one of the safest places of the Underdark, Blingdenstone is under Demons' influence. There, PCs will face the spawns of Juiblex, the Faceless Lord, Demon of Oozes and Gelatinous Beings.
The city, which is recovering from a heavy Drow attack in the previous years, is flooded by oozes, slimes and gelatinous cubes, lead by the Pudding King, a svirfneblin under Juiblex's influence.
PCs will reach their ultimate goal leading the svirfneblin in a battle against the oozes.
At this point the party should have collected i PG enough informations to find a way to leave the Underdark.
In the following post you'll see the final moves for getting out.