Full Moon was to have been the first of four Halloween specials however due to the death of Elizabeth Sladen was never produced. Like the other, proposed Halloween specials it was to have been a live 2011 broadcast and the show's first ever Halloween special.
It would have seen Sarah Jane and her gang encounter the Pagan Gods, Gog and Magog, who were trying to escape an alien spaceship. (The Sarah Jane Companion Volume Three)
It would been succeeded by The Station, another special.