Harthalín believes the meeting of the Masters will take place, but if you are to make use of this information you must learn what location each of them might trust.
'I have had an idea, ${PLAYER}. Each of the Masters of Mordor has walked this land longer than either of us, and they know its out of the way corners better than we could ever hope to do. Even I, who fought during the Siege of Barad-dûr at the end of the Second Age and saw the shape of the land then, cannot pretend to the knowledge of those who seek to rule Mordor now.
'But there is one who has demonstrated such knowledge of this land to us. Do you remember? I do not trust him, for who truly could, but he has watched the movements of our enemies and knows somewhat of their motivations.
'I speak of Zaghárog, ${PLAYER}. The spirit in the stone may have seen more than we, and know of the place the Masters will settle upon for their council.'
The watching-stone inhabited by the spirit Zaghárog is on the road to the Caverns of Fire, in Talath Úrui.
Zaghárog showed you a particular area in Lhingris and asked you to kill the creature there.
The watching-stone inhabited by the spirit Zaghárog is on the road to the Caverns of Fire, in Talath Úrui.
Zaghárog told you to walk to the north-west. Will this provide your answer?
Harthalín is by the road to Nargroth, on the eastern edge of Talath Úrui.