the tardis crew are reunited as guests, and it soon becomes apparent that there are four distinct human cultures represented on the vessel by a small group of humans – ancient greeks, the leader of whom is the philosopher bigon; chinese mandarins and their leader lin futu; princess villagra and representatives of the maya peoples; and kurkutji and his tribesmen, of a very ancient australian aboriginal culture. the urbankans have made periodic visits to earth, each time getting speedier in their journeys. this time they have left their homeworld after erratic solar activity, storing three billion of their species on slides aboard their craft. it seems that the current journey is their last and that they now wish to settle on earth, which they are due to reach in four days.