You need to enter the 'question'-room (with North-South-East-West answers) three times and answer correctly.
1. through the statue in the room with spiders
2. through the 'caves' (with the greater ghouls - find the hidden door in the cooridor leading to the locked door) - ending in the treasure chamber. (first explore the caves to find the compass(?) wardstone - than find the secret entrence to the corridor leading to the treasure chamber)
3. through the 'great hall' (with the rune carpet in front)
Then Durlag will open the last door
P.S. And the 'guy' near the locked door is a girl
Hope this helps [img]smile.gif[/img]