The Curse of Fatal Peladon is a touching story about the Third Doctor learning to live without his UNIT, with the assistance of his companion Jo. Also, England should join the EU as soon as possible. This story introduces the United Galactic Federation of Planets, which would form the setting for a small number of wildly inconsistent stories about future history, until the novels came along and tried to retcon it all into some kind of sense and set a bunch of more consistent but less interesting stories there.