A mysterious black hole is draining away power from the Universe. Even the Time Lords are threatened. The Doctor is also in trouble. Creatures from the black hole besiege UNIT Headquarters. The only person who can help the Doctor is... himself. The Time Lords bring together the first three incarnations of the Doctor to discover the truth about the black hole and stop the energy drain. The Doctors and their companions travel through the black hole itself, into a universe of anti-matter. Here they meet one of the very first Time Lords - Omega, who gave his race the power to travel through time. Trapped for aeons in the black hole, he now plans to escape - whatever the cost. This novel is based on a Doctor Who story which was originally broadcast from 30 December 1972 to 20 January 1973. *Featuring the first three Doctors as played by William Hartnell, Patrick Troughton and Jon Pertwee, together with Jo Grant and the UNIT organisation commanded by Brigadier Lethbridge-Stewart*

UNIT is called in when an important diplomat is attacked in his own home - by a man who vanishes into thin air! The Doctor and Jo spend a night in the 'haunted' house and meet the attackers, who have 'time-jumped' back from the 22nd century in the hope of changing history. Travelling forward in time, the Doctor and Jo find themselves trapped in a future world where humans are slaves and the Daleks have already invaded. Using their ape-like servants, the Ogrons, to maintain order, the Daleks are now the masters of Earth. As the Doctor desperately works to discover what has happened to put history off-track, the Daleks plan a time-jump attack on the 20th century. Featuring the Third Doctor as played by Jon Pertwee, with his companion Jo Grant and the UNIT organization commanded by Brigadier Lethbridge-Stewart, this novel is based on a Doctor Who story which was originally broadcast from January 1-22, 1972.