In the second episode of the four-part story "Four to Doomsday," the Doctor (Peter Davidson) and his companions are trapped aboard a space vessel commandeered by the frog-like Urbankans. Likewise in the same predicament are four other passengers, all apparently earthlings, each from a different race (Greek, Chinese, Mayan, and Aboriginal Australian) and different time periods. First telecast January 19, 1982, "Four to Doomsday, Episode 2" was written by Terence Dudley. ~ Hal Erickson, All Movie Guide