The descendants of the human settlers of the only planet orbiting the star Cepheus, the Terratins were shrunk to a few millimeters in height by the strange spiroid energy waves that suffuse the surface of their adopted planet. When their geologically unstable world threatened to wipe them out, they were forced to accept the assistance of crewmembers of the U.S.S. Enterprise, who agreed on stardate 5577.7 (2269) to transport the tiny Terratins and their Lilliputian city to the far more pleasant world of Verdanis.