Who is he, the mysterious “man with a clock”, whom the good-natured Chinese, the owner of a small restaurant next to Petka’s house, was so afraid of? Could it be that suspicious stranger who for some reason didn’t like Petka’s dog? Maybe his old-fashioned watch with a chain is a secret sign, symbol or password? It is not easy for the five pathfinders to find answers to these and other questions. After all, they are hidden deep underground...