The signal is originating from the plane of Ysgard, traditional home of the Nordic gods. His portal deposits him outside a massive, solitary, craggy peak, rising high over a barren tundra on one side, and a white-capped sea, on the other. The message clearly comes from some source within, and whoever is there isn't terribly subtle about being there, either; a long, sinuous stone path is carved into the near face of the mountain, ending at the entrance to what looks like a dwarven citadel, about a third of the way up the peak. A brief scan of the mountain, however, reveals it to be entirely uninhabited, although quite riddled with hollows.