Many believed for sometime that the Time Lords were all extinct, wiped from existence by the great Time War.
All perished except one. The Doctor himself had survived, believing to be alone until now. But he wasn't the only survivor. One other was protected from the Time War, just as the TARDIS had protected him. Another escaped it. One whom the Doctor knew well, and would soon be reunited with. And so our story begins, on Earth in the far future…

In a house outside of London, a fragile and weak old woman - aged somewhere in her nineties - lies in bed. In walks a young woman aged around twenty-six. She's the old lady's granddaughter, called upon to come to her side. Walking to the bedside, the young woman looks down at her grandmother. Suddenly the old lady turns her head towards the young lady and opens her eyes. With a weak low voice, she begins to speak.

"Nikki, you've come. Bless you, child."

"Yes, Grammy, I am here," replies Nikki.

"I fear the end is near for me," says the old woman. "Before the time comes, I must tell you something."

Reaching around her neck, the old woman pulls out a necklace - upon it, a key. Nikki stares at it and then the old woman begins to explain.

"You see, my child, this is no ordinary key. It unlocks something that doesn't exists on this world."

Nikki looks at her grandma with a look of disbelief, thinking that it's her grandma's failing health that is causing the tales. She decides to listen further.

"The key - which I've worn around my neck for many years - opens the door to a ship, which is called the TARDIS," the old woman says. "It belonged to my grandfather, who left in it when I was younger. After he left me, I felt so alone but I knew I wasn't. For I had your grandfather to be there with me by then. He gave me an identity, someplace permanent.

"You see, Nikki, I'm not from this planet. I'm from a planet called Gallifrey, where I grew up for a time till I began travelling with my grandfather in the TARDIS. We travelled for some time, and had company along the way - my schoolteachers, Ian and Barbara. The way I came to be here was that we arrived in the TARDIS in London in the year 2157, where we found a great battle was being waged between resistance fighters and an evil alien force called the Daleks. With Grandfather's help, we started the blow that drove the Daleks to their deaths. It was 10 years before all that was over. Your mother was born that year. We had been too busy to think of a family before then.

"Life began to have a bright future for the earth, until your grandfather passed away. Soon I shall join him, but before I do I want you to know more, and there's something I want you to have."

Weakly leaning forward, the old woman uses every bit of strength she has to remove the necklace from her neck, reaching forwards to hand it to Nikki. She drops the necklace into Nikki's palm. The moment the key touches Nikki's skin, it sparks. Nikki takes the key and held it up. Suddenly it begins to glow. A light surrounds it. Frightened, she drops the key, which lands on the floor. Bending down to pick it back up, she finds that the key is standing straight up - still glowing, but now making a low humming sound.

In the console room, we find the Doctor reading a book. His mind isn't on the book, though. It's thinking of Rose, left behind on the alternate earth. The Doctor is now alone travelling amongst the stars.

The Doctor sits in the pilot seat with his feet resting on the TARDIS console, just as Rose used to do many times.
He closes his eyes and drifts off to sleep… which is suddenly cut short by the sounds of the TARDIS demanding his attention.

Taking the hint, the Doctor instantly springs to his feet. The TARDIS is shaking vigorously then stops. Something is interfering with the instruments. He tries to override the error but he is locked out. Whatever it is, the Doctor has no idea. All he knows for sure is that he is heading somewhere. The question is, where?

Within moments the sounds of the TARDIS materializing are heard, then nothing. Looking at the monitors, the Doctor begins to work out where he has landed.

"Hmm," he says. "It's Earth. Seems to be the far future, year unknown."

Well, as always, the Doctor is curious. He makes his way to the doors and opens them, exiting the TARDIS.
Outside the air is a cool breeze and everything seems normal. Suddenly he feels a strange sensation that he has been here before. Of course he has - he's been to earth many times. But for some reason, this time feels different.

Scanning the immediate area the Doctor feels a strange force or something directing him. He proceeds onwards, and after a short brisk walk he finds himself standing outside an old farmhouse. He raises his hand and knocks on the door. After a few minutes the door opens. Nikki stands there.

"Yes, may I help you?" she says.

Before the Doctor can answer a strange light begins to be emitted from her hand. It's the TARDIS key, which flies from her hand towards the Doctor. He catches it, and both of them stand looking puzzled at one another.

Then the Doctor speaks. "Where did you get this?" he asks.

"It belongs to my grandmother."

"I must see her,"

"I'm sorry," says Nikki. "but I don't know you - and my grandmother isn't in the best of health."

"Please," insists the Doctor. "I must see her."

For some strange reason Nikki feels that it's OK to trust this man. Stepping aside, she lets him in. Shutting the door, she motions for him to follow down a long hall. They turn towards a room. Inside, an old woman is seen sleeping. Walking over to the old woman, the Doctor realizes he knows her, but can't recall who she is.

The old woman opens her eyes and stares at the Doctor. She, too, realizes that she knows him. Then she speaks.

"Grandfather - is that you?" she asks. Something tells her that it's him. She'd known him when his body was old, but had also met him once when he was in a young body - in his fifth regeneration.

The Doctor stares in disbelief. It has just occurred to him that he knows who she is.

Susan… but it can't be her! He knows that with the destruction of Gallifrey, all Time Lords were wiped from existence. Susan - whom he left on Earth many adventures ago - would have been lost as well. But here she was - he knows it to be her. Leaning forward, Susan hugs him. Though weak, she uses all the strength she has. Nikki stands and watches in disbelief.

Susan then calls Nikki over. She walks slowly towards the two.

"My dear," Susan says. "This is my grandfather - your great-great grandfather."

The Doctor and Nikki turn and stare at each other for a few minutes, then the Doctor breaks the silence.

"So you're my great-great-granddaughter," he says, walking over to her.

Somehow Nikki feels that he is whom he says. Turning back to Susan, the Doctor still has one unanswered question, which was how could Susan have survived the Time War. He walks back and forth for several minutes, then stops.

"Of course – I've got it."

There's a pause.

"What is it, grandfather?" Susan asks.

"I know how you survived the Time War,"

"The Time War? What's that?"

"Oh, you don't know," the Doctor says.

"Don't know what?"

"That all of Gallifrey is gone, and every Time Lord gone wiped from existence. Except now, I know it's not all."

Susan sits in the bed - a sad look upon her face. Tears are forming. She has known, somehow, but hadn't been sure. The day it had happened she had felt something, but had never known until now.

"So how did you survive, Grandfather?" Susan asks.

"Well, the TARDIS protected me from the Time War," he replies.

"So how was I protected?"

"Well, that's what I was getting to," the Doctor says. "You see, you've had the key to the TARDIS all these years. It itself is part of the TARDIS. Having protected me, the key itself acted as a shield of sorts. It blocked the effects of the wave."

The Doctor keeps on with the technical babble until Nikki interrupts.

"OK, Doctor, right - I think we got the point. Sorry."

"I'm sorry," he replies. "I'm just so happy to see Susan again. You remember, Susan - I know it's been long ago, but I never forgot you, and I did promise I would return one day. And the TARDIS never let me forget - nor did it, but why has it brought me here after all this time?"

So why did the TARDIS do that, and why - when Nikki touched the key – had it set off the events that led to now? Well, the reason would soon be found out. As you see, Nikki was on an adventure of a lifetime.

Nikki was soon realizing her grandma wasn't losing it. After all, she had met her great-great-grandfather and now they
had a mystery upon them. Why was the Doctor brought here? Was it to be with Susan in her final moments, or was it for another purpose - perhaps to save Susan?

A short while later the Doctor and Nikki are sitting in the kitchen when a loud humming sound is heard. Both jump to there feet and race off towards the sound. Its coming from Susan's room inside they can see a bright light. Entering they find that the light is surrounding Susan. Both make there way to her. She stares up at them and smiles.

"My time has come," she says. "I've been prepared for it."

Suddenly she buckles up. The flash surrounds her body. Now she begins to change into a form with no features - a white human form. The light becomes brighter. Shielding their eyes, the Doctor and Nikki try to keep looking. The Doctor notices the TARDIS key is spinning as well. Suddenly there's a huge burst of light filling the room. The Doctor and Nikki fall back.

"Doctor!" Nikki yells. "What is happening?"

"I dunno - never seen anything like it," the Doctor replies.

The light dissipates, and when the Doctor and Nikki are able to adjust their eyes once more they are shocked at what they see...

The bed is empty – but standing at the window is the figure of a young woman. She turns and stares at the two. The Doctor and Nikki can see the woman seems to be in her twenties - maybe younger than Nikki. The Doctor steps forward. He can see the TARDIS key hanging from the young woman's hand.

"Susan…" the Doctor says.

"Yes, grandfather. It's me."

"But how? You never finished schooling on Gallifrey. Only trained Time Lords can regenerate!"

"Well, grandfather - I have the TARDIS to thank for that," replies Susan. "It showed me how, and helped me to become a full Time Lady."

Nikki steps forwards. "You're my grandmother… but it can't be. How?"

"Well," the Doctor begins. "Time Lords - which is what me and Susan are - have a way of cheating death..."

Over the next few minutes he explains it to Nikki, who by now is starting to come to terms with what has transpired.

"So the TARDIS helped," he concludes to Susan. "It used the info of the Matrix to complete your journey. That is why I was brought here, so you could regenerate before your final end."

"Yes," Susan says. "I can see that. But that wasn't the only purpose for your arrival."

The Doctor looks puzzled.

"There is a greater calling here," explains Susan. "and you must help me complete that a mission of great urgency."

"Well, one thing I have yet to figure out," says the Doctor. "You survived the Time Wars, yes, but how come I never sensed your presence?"

"Well, grandfather, the TARDIS not only masked me from the Time War. It kept my presence hidden as well till the time was right. You see, it's been my watcher all these years as well… sort of a mother."

"Back to this mission. What is it?" he asks.

"All will be revealed," she says. "We must go now."

The two stand to leave. Nikki walks over.

"Where are you going?" she asks.

"There's something we must do. You're welcome to come," Susan says.