Jonny is missing. Find him and bring him home to Balthas

Find a rope, enter the well in Modoc. You will see many money bags around you. Picking these up nets you one bottlecap and -1 karma each, so you don't need to pick them up. Further into the cave you can find Jonny's BB Gun in the well and finish the quest by talking to Balthas. For a more joyful resolution, next find Jonny in the Slag caves under the Ghost Farm and secure Vegeir's permission to take him home.