 The Doctor, having met another time lord, named Drax, in the caves, teams up with him to try and defeat the Shadow, but the other time lord shrinks him, instead of his captor, then turns the shrinking ray on himself, allowing the Shadow to claim the Key to Time. Meanwhile, everyone finds out that Princess Astra, herself, is the sixth and final segment of the Key to Time. And once it is assembled, nothing stands between the Shadow and absolute power of the Universe...except the Doctor!