Worried about earthquakes damaging his money bin, Scrooge McDuck is determined to find out what causes them. Upon a suggestion by Donald, Scrooge has a shaft dug beneath his money bin to search for faults which might get cracked open by a tremor, but the miners are suddenly frightened away by voices coming from a gigantic cave. The next day, Scrooge, Donald and Huey, Dewey and Louie find strangely round, colorful rocks scattered around the mineshaft. They prepare to descend, but all of a sudden their minecarts are sabotaged, stranding them deep beneath the ground. In the underground, Scrooge and his nephews soon discover that the smooth "rocks" are really subterranean beings calling themselves Terries and Fermies who look like bowling balls with arms and a head, but no legs, and move around by rolling on the ground. The Terries and Fermies can hearradio broadcasts through certain magnetic rocks, which allowed them to learn English - with a southern accent - from listening to country musicradio stations. Terries cause earthquakes by rolling in massive groups of thousands against the giant pillars that support the land on the surface of the Earth, while Fermies cause earthquakes by gathering together in massive numbers and lifting up pieces of the Earth's crust. They treat this as a sports competition: Whichever group causes the biggest earthquake wins the contest and gets the prize, a piece of Ancient Greek pottery that fell down a crevice in Ancient Roman times in the year zero. However, now the Terries and Fermies have assembled for a large-scale bout which would result in Duckburg getting destroyed. In an attempt to stop the earthquakes, Scrooge steals the trophy but is forced to discard his top hat during the subsequent escape. The Terries and Fermies pursue in an attempt to stop them before they can tell the upper world of their existence and thus stall their competition. When that fails, they trigger a series of powerful tremors in order to shake the Ducks back down the shaft; this accidentally causes Scrooge's money bin to dislodge, slide across the shaft and crack open, spilling all his money into the underground. However, since they think of money as worthless garbage, the Terries and Fermies unite for a massive clean-up. Proclaiming Scrooge's hat as their new trophy, they push the money back into the money bin and then seal the shaft to prevent more money from getting dumped on them. The story ends with a professor visiting Scrooge to assure him that there will be no more quakes. But when Scrooge asks him what triggered the tremors, and the professor answers that it was "gas that builds up in fissures as the Earth shrinks", Scrooge slyly winks at his nephews with the words "He shore ain't been around, has he, podners?"
