"Is that you Susan, hm?"
"Doctor, what has he done to you?" Martha sobbed, as the old Doctor dusted himself off, rose, and wandered over to a mirror, using table, chairs and cabinets for support. He looked down at his blue-suited self and snorted.
"Harrumph, I look ridiculous, utterly ridiculous! What was that child?" The Doctor turned, and immediately fished around in his pocket.
"I said, what has he done to you?" Martha replied, tear stains still on her cheeks. The Doctor was getting more and more frustrated by the minute, searching through all the pockets, finding only a sonic screwdriver, three bananas, a spinning top and book. Finally he found the glasses hanging from his collar and stuffed them onto his face.
"And who might you be, child?" the Doctor demanded, still holding onto a table for support.
"I'm Martha! We've been travelling together for the last five months! Do you not remember?"
"Martha? But I was with Vicki and Steven last, and before that was Ian, Barbara and Susan, but not Martha, hm. What incarnation was I in when you travelled with me?" the Doctor said, pacing up and down unsteadily. Martha just looked blank. The Doctor sighed and continued.
"What did I look like child? That is not too dificult a question I presume, hm?"
"You had brown shortish hair, brown eyes, sideburns, normal ears, clean shaven."
"That is enough my child, you obviously did not travel with me, nor my first, second, third or fourth. I wonder which one..."
"But what happened to you?" Martha asked, still looking confused.
"Well it's hard to tell when I don't know which me you were with, but it seems likely that I was aged backwards beyound my regenerations, and it was stopped at around 600, did your Doctor ever say how old he was?"
"I think he said he was about 950 years."
"So the deaging process was stopped about a third of the way through, it could have been a whole lot worse."
"Now can you please explain what is going on!"
"First, we must get out of here, where is the TARDIS, I'll explain when we get there, if I must!"
"We left the TARDIS in the corner of the storeroom, but we need to get out of here first, and the door's locked!" The Doctor produced the sonic screwdriver, waved it in her face and cackled. A short burst of the sonic energy was all that was needed to open the lock.
"Hm, hm! Now, lead on child," the Doctor instucted, using her offered hand for support. Martha lead him a short way down the corridor, before turning into a large storeroom, in a corner of which stood the TARDIS, tall, blue and proud. Martha unlocked the door, and when inside helped the Doctor in, and and he sat on a chair.
"Hm, now I really must change from this ridiculous garb, hm, this place looks ridiculous now." The Doctor pulled himself up and left through a door into the corridor, before entering the wardrobe. Martha pursued him.
"You said you would tell me what was going on in here!"
"Patience, patience, my child, now can an old man have some privacy?" With that, he pushed her outside and slammed the door. Martha strode off to the console room in a huff.
The Doctor searched through the assorted clothes, until he found his black coat, his checked white shirt, his trousers and his necktie, as well as picking up his stick. He ambled out and into the control room, and was confronted by Martha, but before she could speak he held up a finger and began to speak himself.
"I am a Timelord, and all timelords have the ability to regenerate. This means should a timelord become fatally injured, or die naturally of old age, or die for any other reason, then they can renew themselves. They change their appearence, their personality, everything. I, am an earlier incarnation of the Doctor you know, the first, the original you might say!"
"So, what do we do now?" Martha enquired, as the Doctor stared at the central column.
"This 'rejuvenation' technique is not permanent, I am likely to die and regenerate very soon. We must find how he did this, and stop it, so that I don't continue to regenerate until my regenerations are used up."
"How are we supposed to find him? He has a time machine!"
"I have a trace of the time energies this particular type of time machine emits, and I know just the person who can help me find it, hm hm hm!"
"David, can you answer that please?" David went through the hall and answered the door, to reveal the Doctor standing there, with the TARDIS standing just outside. When David just stood and stared, the Doctor swept in and went through into the lounge.
"David, dinners nearly ready!"
"I do hope it's not rabbit again, my child," the Doctor said, poking his head into the kitchen. Susan whirled around, and screamed.
"GRANDFATHER?!?!" Susan charged into the lounge, and ran straight into the Doctor's arms.
"Oh Grandfather, what are you doing here?!"
"I'm having a bit of a problem child, I have had my age reversed, probably by a time reversal field, and now I need to follow the perpetrator, and I need you to help me build a tracer for bianglical vortex manipulator. And I didn't know you could cook?"
"I can't, David is cooking it." David walked in, still looking confused, holding the food and a tea towel. Susan turned to David.
"I've got to go David, I'll only be a second, I promise!" Susan and the Doctor dashed out and into the TARDIS. David listened as the TARDIS left, and threw the towel on the floor in anger, just as the doorbell rang.

"Have you got a sonic screwdriver, Grandfather?"
"I've got it, Susan."
"Thank you Martha," Susan said with a smile as she recieved the screwdriver. "There, finished."
"We'd better plug it into the TARDIS console hadn't we then, hm?" the Doctor said as he collected the complex equipment, and inseted two plugs into two sockets at the back of the console. He switched it on, and read the readings.
"Hm, the tracer says he is in the year 1883, planet Earth, when we are in the right time stream a location can be determined. Shifting timestream, now, location determined, Indonesia, late August."

"What could he possibly be doing in Indonesia?"
"Well, this is a volcanic island, so he's probably trying to destroy the machinery he used, so just in case I did survive I wouldn't be able to use it to reverse the effect, and so would have to spend more time looking for a solution than looking for him. He's covered all the corners, hm," the Doctor explained.
"The tracer indicates that the time machine is in the volcano, Grandfather," Susan said, and Martha looked out over the island to the volcano.
"Is he waiting for the volcano to erupt, so it destroys the machienery? Because if he is, then it's not the best solution," Martha enquired of the Doctor.
"Well my child, he has probably chosen a time when he knows there will be an eruption, or he will trigger an eruption himself, he isn't stupid, hm."
Susan walked back to the console, and began to activate them.
"I'm just going to materiallise the TARDIS inside the volcano," she said as she did so.

"Do you know of any major volcanic eruptions in Indonesia, my child?" the Doctor asked Martha as they poked their heads out of the TARDIS.
"I never was any good at history, perhaps if I knew exactly what island we are on would help," Martha said apologetically.
"It's the island of Krakatoa, Aug-"
"Krakatoa?! The biggest explosion is recorded history was the island of Krakatoa exploding!" Martha exclaimed, getting slightly hysterical.
"When did this happen?" Susan asked, but Martha's reply was cut off.
"Never mind that child, he must have picked this time for a reason, into the TARDIS"
"Doctor, there's the machinery!" Martha pointed out.
"Hm, so it is, and he's set it to trigger the eruption, see, he's hooked it up to that drill, causing a small earthquake, which will set the eruption going, we must get into the TARDIS!" The three of them piled in, and took off, just as the machienery exploded, and the volcano began to erupt.

"How long were you gone this time Susan?" David enquired as he opened the door.
"Oh not long," Susan said as she hugged him. They turned and watched as the TARDIS dematerialised behind them.
Inside the TARDIS, the Doctor sat brooding on a chair, as Martha paced up and down in the console room.
"What are we going to do now, Doctor? Doctor?" Martha turned, as the Doctor stood up, before collapsing.
"Oh no, Doctor!" Martha ran to his side, as the Doctor moaned, and Martha shielded her eyes from a bright flash of light.
"Doctor?"
"Oh my giddy aunt, oh crumbs!"

Sorry, rushed ending :(