The Tenth Doctor and Donna Noble had been travelling together for a few weeks, when a disturbing memory came into his mind. Something had gone terribly wrong in 1977. It stood a chance of changing his own personal history.
"My past is being violated," said the 10th Doctor, "It starts with my 4th self. We have to go to 1977."
"Hey, hang on," said Donna, "4th self? I barely had my only self in 1977!"
"Explain on the way," said the 10th Doctor, setting the TARDIS controls and heading for the latest known time and place inhabited by Sarah Jane Smith.. He had recently met up with Sarah again for the first time since the 5 Doctors adventure, when his 3rd self had come to Gallifrey with Sarah Jane Smith (although a Sarah Jane Smith who had come from 1983 at some point after departing the company of his 4th self in 1976). She had briefly met the 1st, 2nd and 5th Doctors on that occasion, but had not seen the Doctor at all in any of his forms again, until a recent encounter with his current 10th self and Rose Tyler. The issue of regeneration and abandonment of companions had come up, amidst a temporary cat fight between Rose Tyler and Sarah Jane Smith. Since then, Rose had been stranded in a parallel universe and Sarah had gone her own way with K-9 Mk IV, the newly built replacement of K-9 Mk III at the end of that adventure.
(If you can follow all that, you can probably finish writing this story more effectively than I can).
The Doctor knocked on Sarah's door. She came to the door, with K-9 Mk IV following her in the hallway.
"Master," said K-9 Mk IV.
"Doctor?" said Sarah.
"I need your help," said the Doctor, "Something's happening in 1977. You weren't hanging around UNIT at that time. So I don't think you'd likely meet your younger self if I took you back, but you did spend most of your association with me in lengthy travel with my 4th self, ending the year before 1977, a time when my memory is telling me that my 4th self met with an unthinkably crafty teaming of his most threatening opponents. You might be the only person we can count on to help us, and K-9 would be a valuable help to me too."
"1979 again. What fun!" said Sarah, noticing Donna Noble standing behind the Doctor, "Is this your latest …?"
"Latest what? Now listen hear Missy …" began Donna.
"Let's not go through that again," said the Doctor. We should head for the TARDIS. It's parked in your front yard, just out of view."
K-9 Mk IV, Sarah Jane Smith, Donna Noble and the 10th Doctor went into the TARDIS, and the Doctor set the controls for London, 1977.
London, 1977…
The 4th Doctor and Leela and K-9 Mk 1 had materialized the TARDIS in Hyde Park.
"Always wish I'd gotten the Chameleon Circuit repaired," said the Fourth Doctor, "Still this is one of the few times and places where the TARDIS looks almost normal. It was disguised as a London Police Box when it got stuck in its present form. Let me show you around."
"Master?" said K-9.
"You could come too. Here you'll just be mistaken for one of those remote control children's toys. Try not to stun anyone. It'll help you keep in character," said the 4th Doctor, "Now Leela, I'll have to see what's in the wardrobe that looks more suitable for this century. We passed you off as a local in Victorian London once."
The Doctor selected some suitable clothes, and Leela changed into them, and did her best to conceal her knife.
The Doctor, K-9 and Leela went walking through Hyde Park and were suddenly arrested by members of MI5.
"Master, request orders," said K-9 Mk 1.
"Don't do anything yet, K-9," said the Doctor, "I want to know what's going on. The Brigadier should have kept me in good standing with the government after the Zygon affair and the Android Invasion."
The Doctor and Leela and K-9 were taken to a secret complex and put into a court room for an unusual hearing. He instantly recognised the man who purported to be the head of MI5. It was the Master, as he had looked during the times of the 5th, 6th and 7th Doctors' encounters with him. It was the Master who had stolen the appearance of Nyssa's father, after sacrificing the man on Traken to steal his body. Since then, Nyssa had become one of the 5th Doctor's travelling companions, having witnessed the 4th Doctor's regeneration into the 5th. She had eventually settled on Terminus. This was the Master just after the 7th Doctor had seen him on a planet of cat like creatures.
Using the unique gift of Timelord recognition, the 4th Doctor was still able to identify this version of the Master whom he had not yet met.
"We're not supposed to meet yet," he said, "You're messing with the flow of time itself."
"Oh come now Doctor, let's not be melodramatic. Are you not keen to find out how I turned MI5 against you and keep the knowledge from your old friends at UNIT?"
"It is something I'd wondered about for the last few seconds, or at least a few of the last few seconds," said the 4th Doctor.
A woman entered the room.
"Doctor, meet Mrs Merry Brightspouse," said the Master.
