There should have been a number of talks and hints of how the underground operation is related to the surface activities of the Iron Throne.
If you had Jen'lig you will also have has a quest about a dead cithyanki, a silver sword and a dragon of Tiamat.
You find a silver sword with the Shar Nadal.
A group of githyanki would wait for you when you come to the surface and you could make a deal for some information exchange and part peacefully. (If Jen'lig is with you, there is extended content here).
You also get first information about Jarlaxle.
When you leave the tunnels and reach the cave in bandit camp, you would meet a drow priestess of Eillestrae, who foreshadows a major event for Sandrah.
There is a talk about leadership and responsibility when you are back on the surface and you have to deliver the truth about his nephew to Otho.
(You reactions and answers to the various events have impact on later events, this may not be obvious right away.)