The Doctor must save the Time Lords from a mysterious black hole... with himself, in a new edition of a Doctor Who classic

Terrance Dicks worked on scripts for The Avengers as well as other series before becoming Assistant, and later full Script Editor of Doctor Who from 1968. Dicks worked on the entirety of the Jon Pertwee Third Doctor era of the programme, and returned as a writer - scripting Tom Baker's first story as the Fourth Doctor: 'Robot'. His later script writing credits on Doctor Who included the 20th anniversary story 'The Five Doctors'. Terrance Dicks novelised many of the original Doctor Who stories for Target books, and has written original Doctor Who novels for BBC Books. Bob Baker and Dave Martin, original script writers for 'The Three Doctors', wrote extensively for television during the 1970s and 1980s both as a team - on series including Z Cars, King of the Castle and Target - and separately. They also wrote a total of eight stories together for Doctor Who (with Bob Baker writing another on his own) and created the 'character' of K-9. Dave Martin died in 2007.