Disguise yourself as an Iron Rune Overseer, intercept the message from Loken, then report to Mountaineer Kilian at Prospector's Point.
1x Message from Loken received
Using the images you've captured, I've created everything you need for your overseer disguise kit. You'll make a fine iron dwarf, if I do say so myself.
Take the kit with you to Dun Argol, use it to disguise yourself, then go to the easternmost building on the broad middle tier of the city.
There, you should see a pedestal where the thane and overseers receive their orders from this Loken. Activate it while disguised and learn all you can from the communication.