Qi to put a Rainbow Shell in the middle of the train track. If you place a battery pack inside the box you’ll find a note from Mr. You can either find a lost book and get the quest from that or you can inspect the box that is in the bus tunnel. The other quest he offers is a lot more elaborate and definitely one of the weirdest available in Stardew Valley.
When you complete that quest you get 10,000 gold from Mr. He offers you another challenge, to get to the 25th level of the Skull Cavern which is located in the desert. The first one is triggered when you complete all the levels of the mine.
