Watch for the omens. The first segment of the Key to Time. But it can't be, can it? Go on.
Plan: A: the second segment; Q: What segment of the Key to Time is the TARDIS seeking? A: an icy world; Q: Where does the TARDIS head for the second segment of the Key to Time? A: a populated planet; Q: What should not be there? Summary: In seeking the second segment of the Key to Time, the TARDIS heads for an icy world but lands on a populated planet that shouldn't be there.