The dwarves of Heithur Ironfist's company have fallen upon some misfortune near the Last Bridge, and the stones they were transporting to Glóin in Rivendell were lost.
'Clearly, misfortune befell my companions. My dwarves may be lost now, but the stones they were escorting can be recovered from whomever or whatever has stolen them. This we must do, ${PLAYER}.
'As I was returning from Glóin's camp to meet my companions, I saw a large number of cave-claws along the road, especially to the north of the road. Barachen tells me that the ruins of Ost Dúrgonn lie near there as well... the old fortress of Rhudaur would attract creatures such as cave-claws, for the vermin devour stone. It may be that whatever frenzy has drawn them out of their caves has also driven them to attack armed caravans. Alas, the stolen stones would be just such a prize as might cause the cave-claws to swarm so.
'Would you investigate Ost Dúrgonn for any signs of the stones? As with many beasts, often the pack-leader keeps the choicest morsels, and these stones would certainly be that. Perhaps they yet survive within their foul den.'
Cave-claws infest the ruins of Ost Dúrgonn, north of the road and Barachen's camp.
Heithur Ironfist believes that the cave-claws of Ost Dúrgonn might have carried away the stones that his company was bringing to Glóin and perhaps swarmed in such strength as to defeat the dwarves.
Heithur Ironfist is at Barachen's camp, east of the Last Bridge and south of the road, on a sloping hill in the shadow of tall cliffs.
You have learned from Tóki Whitebeard that the stones his company was transporting have been stolen by trolls, apparently aided by the monstrous cave-claw you defeated.