Intrigued by the ancient humans on board the Urbankan ship, the Doctor and his companions decide to explore further. The Doctor and Tegan, separated from Adric and Nyssa, learn from Bigon the truth about the cultural representatives.
The doctor figures that the Urbankans have visited Earth several times over thousands of years, with each visit coming closer together, but this time the Urbankans have come to stay. Bigone reveals how he and the other cultural representatives, taken at each visit, have lived so long.—statmanjeff