The Three Doctors DVD

UNIT HQ comes under attack by an alien force, and the Doctor has no other option but to call on his own people, the Time Lords, for help. Breaking the first Law of Time, the first two Doctors are lifted out of their time-streams and sent to help the third. But in a universe of anti-matter, an all-powerful figure from Time Lord history is waiting, and even three Doctors may not be enough to stop him...