The Three Doctors and Hatters

The Third Doctor and Hatter remain stranded on Earth, assisting UNIT in defending the planet, when our Time Lords find themselves being hunted by a new foe. Gallifrey and the Universe are in danger, and the Doctor and the Hatter have no choice but to work with their past selves to save it from the ancient Time Lord, Omega. Antimatter, bubble creatures, and an oblivious Time Lady.