I know what you're thinking. What the----? Let me enlighten you. Once upon a time in the 1980s, there were two series. The long-running Doctor Who, which in its first incarnation, ran from 1963 to 1989, and The Tripods, which was, at it said in the opening: "Based On The Tripods Trilogy By John Christopher." The first two seasons, (series in Britain), were based on the first two books of the Trilogy, The White Mountains, (1967), The City of Gold and Lead, (1968). However, before the third season, (third series), could begin, there was a strike at the BBC. Doctor Who now had low ratings. Doctor Who was on the verge of being canceled. So what could be canceled instead of the venerable Doctor Who? The Tripods. The third season, if it had been produced, probably would have been based on the third book of the Trilogy, The Pool of Fire. Would there have been a fourth season? I don't know. Maybe. If so, it probably would have been based on the fourth book, When The Tripods Came, (1988), which was the prequel to the original Trilogy.