I am looking for a picture book that I enjoyed when I was a child in the late 70s. It was hardbound and told the story of a man who had a long-nosed coupe and inherits/comes into a mansion and after a foggy drive there and inhabiting it discovers it is haunted. He discovers a secret tunnel underground (under a lake?) and ultimately makes friends with the ghost and I believe is led to a stash of treasure. I loved this story as I scared easily but was fascinated with ghosts, and in recollecting it reminded me slightly of Edward Gorey’s work. I think he might have been a bit Sherlockesque with a coat, hat and pipe. Had a very 60s/70s style and sensibility in the illustration. Would love to have a copy. Thank you for your sleuthing!