The ghost is in the room you're in now. Throg just happened to notice it first.
The ghost floats toward the warriors. It has the appearance of an elderly dwarf. The ghost says, faintly...
"Well, what took you so long? I've waited five years for that cowardly cur Ironbeard to come and avenge me. And he can't even be bothered to come himself? If he had to send someone else, couldn't he have sent a less hopeless bunch? You did make it this far, though, I suppose...
Well, I suppose we'd better get on with it."
The ghost turns and walks through the northern wall.