TEN
Martha crashed for a couple of hours. She was exhausted. Time was all wonky inside the TARDIS, of course, but she estimated that they had been on the go for about eighteen hours. As she closed her eyes, she laughed to herself. She'd begun the day in a bikini, had spent time in the rain forest, and the bulk of it in ski country U.S.A. Now, she was in a back-alley of an ancient city in northern Africa. Life had a topsy turvy way. Well, life with the Doctor, anyway.
When she returned to the console room a bit refreshed, the Doctor was very carefully pouring Fifal's water sample into a narrow test tube that seemed to be attached to an arm of the TARDIS.
"Feel a bit better?" he asked.
"A bit," she replied. "But I'll still need an awfully good night's sleep when this is all over. And a shower."
And a good, healing shag. Like an exorcism – release our demons, she thought, but she didn't say it. She didn't think it was quite the time.
She watched him pour. "So, first it's the air, now it's the water?" asked Martha.
"Take a look," he said, without looking at her, and he turned the monitor to face her.
"What's that?"
"The TARDIS is tracing an element of the Earth's interior that is not human or Earthly in origin," he said, finishing his pouring. The TARDIS seemed to swallow the sample, and the Doctor stood back and waited. He walked over to the screen to show her. "See? This is an ancient and foreign mass, old as the Earth itself."
A pink spot on the screen was forming. The middle bit was just a blob, but arms were starting to form, it seemed, as the TARDIS detected more and more. It made a loud gurgling sound as it analysed the water sample. The Doctor looked up at it, frowned, and stroked the console comfortingly.
"That's what's at the centre of the Earth?" Martha asked.
"Yep. It's a ship."
"Oh my God! What sort of ship?"
"What kind of a question is that? How many sorts of ships are there? It's meant for travelling from one place to another."
She looked at him as though she felt he were being extremely tedious. "Well, who put it there?"
"A species called the Rachnoss," he said. "It may not surprise you to learn that they were vicious creatures with shiny red faces and completely black eyes."
"Ohhh," Martha whispered. It almost came out as an exhale. "Their ship is contaminating the Earth?"
The Doctor nodded. "They had a drug. It was called Vitiatus. Well, they called it a drug, we called it poison. They were a peaceful enough race, used to mind their own business and stuff, until they got hold of the drug. Their faces were a warm pink, their eyes had irises and whites and pupils like yours and mine. But the entire population eventually became addicted to the drug because it made them strong and powerful and euphoric. But it also made them vicious and bloodthirsty and unreasonable, so the Time Lords drove them into exile and they nested at the center of a newly-forming planet: this one. That was before my time, of course."
Martha nodded, still staring at the screen.
"They kept enormous reserves of Vitiatus on their spacecraft... do you see those arms coming off the centre of the blob there on the screen?"
"Yeah."
"I'm pretty sure five of those are stuffed with their supply of Vitiatus. It's, well... leaking now. Probably started happening just a few days ago."
"Five arms?" she asked, more of herself than of him. "Let me guess. One of them extends out to where Tahiti is, another to Brazil, another to Colorado, another to Egypt..."
"And that means there's one more. I'm guessing it will be in central Asia someplace, but we'll have to wait and see. And blimey, that one will be tricky."
"Why?"
He took a deep breath. "Well, believe it or not, it's the Rachnoss ship that causes the Earth to be centred upon the elements."
"You mean like Hydrogen and Oxygen?"
"No, not those elements. I mean air, earth, fire, water."
She raised her eyebrows with curiosity and a dawning realisation. "Oh, those elements."
"The Rachnoss' planet operated entirely on five things: air, dirt, fire, water... and a mysterious fifth element that no-one has ever been able to decipher. Everything they were, everything they had, everything about them was a balance of those five things, including their transport."
Martha stood with her mouth open. Her brain was catching up slowly. Finally, she said, "The air in Tahiti was contaminated."
"Yes, because the air compartment of the ship is leaking Vitiatum into that part of the Earth. And in Brazil, it was in the dirt, the earth, and the trees in the rainforest were leeching the Vitiatum and putting back out as oxygen. That's why it looked like the air there was contaminated too. Well, it was, but only by way of the soil."
"And," Martha said, her eyes lighting up. "That's why the TARDIS said it was every species of tree!"
He smiled at her, and nodded once. "In Vail..." he began.
"It was the fire."
"Yes. It afflicted people who had close proximity to fire for long periods. Campers and socialites who hung about in posh lodges with huge fireplaces for days on end, they were the ones taken in. Walter Morritz got the brunt of it because he was literally down there in the common room every night of the season, standing two feet away from the fire."
She exhaled with awe. "And here in Egypt..."
As if to finish her thought, the TARDIS' arm appeared again with an empty test tube. A small screen read-out in Gallifreyan displayed some results. The Doctor glanced at it, and said, not surprised, "It's in the water."
"We were told not to drink the water in Cairo when we were here as kids," she said.
"Good advice. The water here isn't great anyway, and the tourists and upper-classes don't drink it, they import bottled water from Europe or Asia. But the poorer classes, they have no choice but to drink from the taps, and... there you have it. That's why there seems to be such a clear demographic line in Cairo."
"So, if you're right, and the next 'drop site' is in central Asia, we don't even know how it's going to be deployed, do we? If no no-one has ever worked out the fifth element..."
"Then we just have to jump in and see. We'll let the TARDIS guide us, and hope for the best."
"Do you think it's something tangible? Like wood or stone?"
"Could be anything," he said. "But the other four elements are movable, oscillating. Not to mention the mystery surrounding it... it's doubtful that it's something as stationery or as banal as stone."
"Hm," she sniffed. "This is rubbish."
"Yeah. We'll just have to keep an eye out for new reports of disease."
Martha lit up. "But wait! Maybe we don't need to. It's not really a disease at all, is it? It's a high. Highs wear off, don't they?"
"Yes, that's the good news. Unfortunately, there is bad news: we don't know how long the supply of Vitiatum will last. And when it does run out, what will the withdrawal symptoms be like?" He raised an eyebrow, which indicated pretty bloody ugly.
"Well," she contemplated, leaning against a rail. "If the Rachnoss have been down there for billions of years, since the beginning of the Earth, how much longer can the supply last?"
"They haven't been using it the whole time," he explained. "They were sort of... incubating for a long, long time."
"They were?"
"Yes."
"Why past tense? No more incubating?"
"No."
She looked closely at the screen again. "There's no one left alive down there?"
"Not anymore, no," he answered stoically.
"What killed them, time?"
He sighed. "They drowned."
"Drowned? At the centre of the Earth, they drowned?"
"Yes."
"That's mad."
"I agree."
"Doctor?"
"Yes?"
"Why won't you look at me?"
He didn't answer. He said, "We have bigger problems now, though, because as you've said, they probably brought a supply that would last billions of years, and until a few days ago, it's gone unused. By the time it does run out, the Earth will be swallowed up by the sun, and between now and then, the entire human population could be affected and have killed each other."
"So shouldn't we be trying to find an antidote, or trying to fix the leak or something, instead of trying to work out which city is going to explode next?" she asked.
"But the thing is, Martha, everything about the Rachnoss is a balance of the five elements. If we can stop the final spread, the one deployed through the fifth element, then we can throw the whole thing off-balance. I think that would force the drug itself into retreat, and possibly cause the Rachnoss ship to power down and lie dormant until... well, until the day the Earth dies."
"Okay then," she said. "I'll meet you in front of the telly in fifteen minutes. I'm going to make myself a sandwich, want one?"