My Buried Treasure

"This is a true story of a search for buried treasure. The only part that is not true is the name of the man with whom I searched for the treasure. Unless I keep his name out of it he will not let me write the story, and, as it was his expedition and as my share of the treasure is only what I can make by writing the story, I must write as he dictates. I think the story should be told, because our experience was unique, and might be of benefit to others. And, besides, I need the money." 

The narrator accompanies a former school associate, referred to as Edgar, on a treasure hunt... Upon their return to civilisation, he is quite appalled at the outcome of this trip...