Thaddeus Kanner

 was an expert mountaineer and often explored for mystical beings. He went up Ben MacDui with the Seventh Doctor, Alistair Gordon Lethbridge-Stewart and Niamh Godec and didn't like advice. He was stubborn and didn't head advice. He wanted to hunt the Grey Man. After looking at the Grey Man's face he started acting paranoid. (AUDIO:The Grey Man of the Mountain)