Quickbeam sent you to explore Gemyndsted and prevent invaders from ruining or looting of its long-lost secrets.
'There are some places where Isengard still stands that we cannot reach. Gemyndsted, a small library of ancient Men, is one of these places. The White Hand must be destroyed everywhere. Saruman's influence there must be ended.
'Speak to me again and I will show you where this ruin lies.'
Speak with Quickbeam to travel to Gemyndsted.
Having defeated the leader of the invaders in Gemyndsted, you prepare to return to Quickbeam and inform him of your success.
Quickbeam is at Derndingle.