(Styggron enters, holding the virus and his ray gun.) (The camera cuts back to the Doctor and Sarah.) DOCTOR: Because they'll reach Earth before the ship. FARADAY: Kraals?
Plan: A: Earth; Q: Where do the Doctor and Sarah reach? A: the Kraal invasion; Q: What do the Doctor and Sarah warn the research centre about? A: Styggron; Q: Who unleashes his virus? Summary: The Doctor and Sarah reach Earth and try to warn the research centre about the Kraal invasion before Styggron unleashes his virus.