Birth of a Renegade ( short story ) Birth of a Renegade was a short prose story published in 1983 by the " Radio Times " in its " Doctor Who 20th Anniversary Special " . It was intended to reveal Susan Foreman ' s origin . These accounts of Susan ' s origins have not been reflected in any other source . The story states that Susan is not in fact related to the Doctor , but is instead a descendant of Rassilon . This is a retcon which goes against the intent of the original programme makers who devised the character of Susan as the Doctor ' s granddaughter . A different account of Susan ' s origins , in which she is not exactly the Doctor ' s granddaughter , but instead the granddaughter of the Other , who was later reincarnated as the Doctor , is found in the novel " Lungbarrow " . The impetus to say that Susan was not actually the Doctor ' s descendant came from the belief , widely held among fans in the 1980s and 1990s , that the Doctor is asexual , and thus could not have any actual offspring . This belief was also the official policy of producer John Nathan - Turner , who was often quoted as saying , " There ' s no hanky - panky in the TARDIS . " Thus , this retcon by script editor Eric Saward was in tune with the intentions of the 1980s production team , even if it was at odds with the intentions of the original 1960s production team . In the 21st century revival of " Doctor Who " , the Doctor has been depicted as a sexual and occasionally flirtatious being , and he has referred to himself as having been a father ( in TV : " The Empty Child " , " Fear Her " and " The Doctor ' s Daughter " ) , so the notion of him also being a grandfather is generally no longer considered an issue . In the 2013 episode TV : " The Rings of Akhaten " , the Doctor , for the first time since the revival began , explicitly states that he has a granddaughter . Summary . Tegan is not happy when the Fifth Doctor decides to answer a distress call from Sector 19 , in the spiral of Alpha 4 , a remote area on the fringe of a supernova . Arriving near the source of the signal , the Doctor is disturbed to find it is coming from an enormous battle cruiser . The cruiser appears undamaged . Unlike other warships , it doesn ' t carry any identifying insignia or identification . The Doctor , Tegan and Turlough are even more alarmed when they find that the TARDIS is being drawn to the cruiser by a tractor beam that is somehow using the TARDIS ' own power against it . The Doctor , working under the console , shuts off the TARDIS ' s power for a moment . There is enough energy left to dematerialise when the break in power releases the TARDIS from the tractor beam . The TARDIS materialises safely onboard the battle cruiser . They explore the vast craft in near total darkness — bar the minuscule light from the Doctor ' s pen torch . The Doctor , Tegan and Turlough are blinded and disorientated by a bright light when a door opens . A moment later they are prisoners of three Cybermen who appear to be assisting . The Master reveals that the battle cruiser is his TARDIS , disguised as a battle cruiser ( with his working chameleon circuit ) to suit the Cybermen . The Master ' s plan is to bring the Time Lord s to their knees , not by war but by " securing power by legally exploiting the constitution ! " As they are marched through the TARDIS corridors , the Master talks of Gallifrey ' s past . He recounts the final corrupt days of Lord President Pundat the Third . The Master remembers the Doctor as a crusty , eccentric man , one of the finest TARDIS engineers ever . The Master remembers more than the Doctor , who realises he has had selective memories wiped – just as the Master had told him . The Master explains that students revolted against Pundat the Third but were ruthlessly put down . The students wanted to replace Pundat ' s rule ( in which the Lord President chose his own successor ) with Rassilon ' s Law , hereditary rule by a descendant of Rassilon . The students had tried to recruit the Doctor , but he he had decided to side with the status quo , the constitution and Lord Pundat . When Pundat died of stress soon after the revolt , his chosen successor was the evil Chancellor Slann . The students had found the last of Lord Rassilon ' s descendants : Lady Larn , a seven - year old child adopted by Councillor Brolin . They decided on a second coup . Yet in trying to convert the Doctor , the students were overheard . The Doctor , innocent of the students ' revolt , was too highly respected to be terminated like the other students . It was decided to wipe parts of his memory . Bloody reprisals against the students followed , and the Doctor decided to leave Gallifrey in a TARDIS . As it happened , the Lady Larn was hiding in the same TARDIS that the Doctor stole ; the Doctor knew her as Susan and she affectionately called him " grandfather " . The Master , Tegan rightly guesses , was behind both student uprisings . Believing the students ready for the second , he assassinated Lord President Slann . However , the students weren ' t ready and the Master fled . Once more , claims the Master , Gallifrey is leaderless and politically unstable , the people are crying out for leadership , for a descendant of Rassilon . The Master plans to return with his army of Cybermen ( to whom he has promised the knowledge of time travel ) and rule with Susan as his puppet . However , the Master realises that Doctor , his biggest adversary , must be disposed of first . When Susan is reunited with the Doctor , she refuses to help the Master . She defends the Doctor from the Master and his Tissue Compression Eliminator . As the Cybermen move to separate the Doctor and Susan , the Doctor launches himself at the Master , knocking the Eliminator from his hand . Susan fires as the Cybermen close in . The Master tells the Cybermen not to shoot lest Susan be killed . In the stalemate the Doctor leads his companions back to the TARDIS . With the Master ' s exposed roundel s in the corridor draining the energy to maintain the vast battle cruiser , Susan stops and fires the Eliminator . The damage destablises the Master ' s TARDIS . The Doctor , Tegan , Turlough and Susan just make the safety of the Doctor ' s TARDIS . The Doctor sets the co - ordinates to return Susan home . Outside , the Master is consumed by hate as the walls around him collapse and his TARDIS disintegrates , but the Doctor believes that he hasn ' t seen the end of him .