If Ergothorn can be trusted, a warband of uruks marches on Zudrugund from the south, with orders involving Nár that could endanger the errand of the Grey Company.
This quest is meant for a fellowship. If you choose to undertake this quest solo, you will receive an Inspired Greatness bonus, but the challenge will be great.
You have come with Radanir to Zudrugund in pursuit of the uruk-band.
Candaith is further up the path to Zudrugund.
Núrzumgrat has left a mighty troll to defend the span below Zudrugund. It must be defeated if you are to reach the top.
Now that the Defender of the Span is defeated, you can approach Zudrugund, where the leader of the uruks confronts the dwarves.
Nár is outside Zudrugund, and you should speak to him now that the uruks are defeated.