Born to be the sixth and final segment of the Key to Time. Where is the Doctor? What colour? The Marshal. ROMANA: That the sooner we hand this over to the White Guardian
BOTH: The better! DOCTOR: Unable to distinguish between the White Guardian and the Black Guardian.
Plan: A: the Marshal; Q: Whose plan did the Doctor and Romana prevent? A: the last segment; Q: What part of the Key to Time does the Doctor and Romana discover? A: the White Guardian; Q: Who gave the Doctor and Romana the mission to complete? Summary: The Doctor and Romana prevent the Marshal from concluding his plan and discover what the last segment of the Key to Time actually is. They then encounter both the Black Guardian and The White Guardian in their effort to conclude the mission given to them by the White Guardian.