According to the legends of Gallifrey, and the superstitions of this planet, it's fairly certain that the Fendahl is made up of twelve Fendahleen and a core. Come on. DOCTOR: Leela? Get out while you still can! Got it. TYLER: The what?
Plan: A: one; Q: How many archaeologists are transformed? A: a massive implosion; Q: What is threatening the Fendahl? A: existence; Q: What do the Fendahl and its Fendahleen components start coming into? A: the Doctor; Q: Who is the only one who can stop the Fendahl? A: Leela; Q: Who is the Doctor's partner in stopping the Fendahl? Summary: With one of the archaeologists transformed and a massive implosion threatening, the Fendahl and its Fendahleen components start coming into existence while the Doctor, Leela and the Tylers do what they can to stop it.