DOCTOR: Cybermen have an inbuilt distress signal. LYTTON: I'm not working for the Cybermen. PERI: And achieve what? So is history and the web of time. The Cybermen are hibernating. The Doctor may have interfered with the vastial. To do that, they must destroy Earth.
Plan: A: The Doctor; Q: Who discovers that the Cybermen are involved with the strange distress signal? A: Peri; Q: Who helps the Doctor discover who Lytton is working for? A: time travel; Q: What do the Cybermen want? Summary: The Doctor discovers that the Cybermen are involved with the strange distress signal. Peri and the Doctor discover who Lytton is working for and do their best to keep the Cybermen from gaining time travel.