Kate Stewart, head of Scientific Research at UNIT, was overseeing the dousing of fires from an explosion when the TARDIS materialized down the hall. The Doctor stepped out of the TARDIS and was met with fifteen gun barrels pointed at him.
"Definitely not the fourth moon of Satacalista," he observed.
"Doctor!" exclaimed Kate with relief. "Guns down, gentlemen."
"Kate! Hello," said the Doctor. "How are you? Long time, no see. At least I think so…what year is it?"
"It's good to see you, Doctor," said Kate.
"There seem to be a lot of chaps in hazmat suits," he noticed. "Has something happened?"
"I was rather hoping you knew more about it than we do," Kate admitted. "There was an explosion in one of our labs early this morning. No one was seriously injured, but preliminary analysis points to sabotage. The explosion was fairly localized, although the fires reached a radius of twenty meters. We don't know who did it or why."
"No cameras in the lab then?"
"That's the strange thing," she said. "We captured the whole thing on camera but there's no sign of any intruder who might have planted the bomb, nor is there any sign of whatever set it off. Our first thought was remote detonation, but it had to have been done from inside the facility; and even then the signal would go through lead-lined walls."
"Can I have a look?" asked the Doctor.
"Please do," she said, leading him to a computer and playing the recording of the explosion. "We've already had several different operatives scan the footage. So far: nothing. The detonator appears to have burned up in the fire, so we've nothing to go on with that either."
"Something's wrong with this recording," said the Doctor, continuously rewinding it to seconds before the explosion and playing up until the explosion begins.
"What's wrong?" asked Kate.
"I don't know yet," the Doctor admitted. "But there's definitely something."
"I have to check on the other investigators," Kate told him. "Shout if you find something."
The Doctor waved vaguely at her in acknowledgement, and she left him with the video footage. The Doctor put on his reading glasses as he studied the same ten seconds of footage. He's so engrossed in it, that he barely noticed the arrival of another woman who quietly watched the recording with him.
"Maybe you're using the wrong glasses for this," she suggested after a moment.
"Sorry, what?" asked the Doctor, not taking his eyes from the screen. That's an unfortunate mistake on his part, because if he'd taken the time to look at the speaker he'd have noticed how much trouble she was having maintaining her visibility. She flickered in and out of sight, and when she could be seen she's blurry like a photograph of a rapidly-moving object.
"If you're looking for something that doesn't exist, reading glasses won't help you see it," she pointed out. The Doctor was about to argue, when an idea sparked him.
"No but hang on!" the Doctor said excitedly. He emptied his pockets—cluttering the table with various odds and ends—until he found what he was looking for and replaced his reading glasses with his 3-D ones. "Void-stuff!" he declared victoriously as a red and blue silhouette of a person appeared on the screen. "But how are you possible?" he asked the recording. "You're made entirely out of void-stuff: you don't exist. Hang on; how did she know that. How did you know that?" he asked, turning towards the woman who was no longer there.
"Find anything yet, Doctor?" asked Kate, returning.
"Yeah," he replied slowly, still looking around for the mysterious woman. "Yes, sorry. Take a look at that," he instructed, putting the 3-D glasses on Kate. She stared at the screen in amazement.
"What am I looking at?" she asked.
"Your bomber," he told her.
"So that thing is what bombed our lab?"
"But why?" asked Kate. "And what is it?"
"Void-stuff," the Doctor told her. "You can see it on me too," he added, waving his hand in front of her to show her the blue and red trail that followed it around. Kate waved her own hand in front of her eyes.
"There isn't any on me," she observed.
"That's because you've never been through the void," the Doctor explained. "It's this sort of non-space between different universes. I traveled to a parallel universe once—well, more than once…it's a long story—so I have it on me. But see, that person on the screen: she's nothing but void-stuff."
"So what does that mean?" asked Kate. "Is she from the void?"
"No, because that is impossible," said the Doctor. "Nothing can survive in the void: it's just…well, nothing."
"So what is she then?" Kate wondered.
"I don't know," the Doctor said.
"Do you like games?"
The Doctor and Kate nearly jumped out of their skins.
"Where did that come from?" asked Kate.
"Under your chair," said the disembodied voice. "All the way under." The Doctor reached under his chair and found a communicator taped to the bottom of it.
"Who are you?" he asked.
"Camera four," she told him. The Doctor ran over to the CCTVs and switched over to camera four. The room was empty, aside from his TARDIS.
"There's nothing on camera four," he replied.
"Doctor," said Kate, thrusting the 3-D glasses back on his face. Waving at him on the screen was the woman made of void-stuff. Every few seconds she flickered into visibility, but the rest of the time she was pure void-stuff.
"You set off the bomb," said the Doctor.
"Yes, I know," she replied into the communicator.
"But why help me find you? Why did you tell me what to look for?" he wanted to know. To Kate, he explained, "She was here earlier. She gave me the idea about the void-stuff. But I wasn't paying enough attention: I didn't know who she was."
"Toggle," the stranger replied.
"You asked who I am," she said. "My name is Toggle. Now it's your turn to answer my question."
"What question is that?"
"Do you like games?" she reminded him.
"Depends on the game," said the Doctor, sitting down on a swivel chair and spinning. "For example, I'm rather fond of chess but I find noughts and crosses a bit dull."
"How would you like to play a different sort of game?"
"I'm a bit busy at the moment," replied the Doctor. "Investigating an explosion and all."
"Suit yourself," Toggle said, shrugging. "I'll wait until you're ready." Then she unlocked the TARDIS door, swung open the door and walked casually inside. The Doctor leapt to his feet.
"How did you do that?" he demanded. Toggle sighed heavily into the communicator.
"You make it way too easy," she replied. "I didn't even have to pickpocket you." The Doctor searched his pockets, then ran back to the other table and searched through the belongings he'd scattered there. Not surprisingly, the TARDIS key was missing.
"Doctor, what's wrong?" asked Kate.
"She's stolen my TARDIS key," he said.
"Okay, but she can't fly it can she?" Kate reasoned.
"Maybe she can. She shouldn't even exist, remember?" the Doctor said.
"Are you ready yet?" asked Toggle. The Doctor picked up the communicator and took a deep breath before replying.
"You should know that I don't respond well to threats," he told her.
"I'm not threatening you, Doctor," she said. "I've already stolen your TARDIS: what more is there to threaten you with? Now, would you like to hear about my game?"
"Does it involve giving me back my TARDIS?" he retorted.
"Yes," said Toggle, "if you win, that is."
"And what's stopping me from taking it back by force?" asked the Doctor.
"Oh come off it, you know you can't," Toggle scoffed. "I've locked the door and you don't have a key, so there's no way you can get back in here without my say-so."
"What happens if I lose your game?" he wondered.
"Hang on, I haven't even told you what we're playing yet," she said. "First, look behind the screen."
"Are you referring to the cannibalized vortex manipulator you left for me?" he asked.
The vortex manipulator in question had been stripped of all the controls. In their place were a receiver and a mess of circuitry, allowing it to be controlled remotely.
"That's the one," Toggle said brightly. "Go ahead and put it on." The Doctor grudgingly strapped it onto his wrist.
"Doctor, you're not going to play along with this," said Kate.
"It doesn't look like I have much choice," the Doctor replies.
"There are three rounds to the game, each more challenging than the last," Toggle explained. "If you win the first round, you get to move on to the second, and if you win that you get to go to the third. The game is called 'can you save them?' In each round you'll face a different peril; the object is to save the people threatened by it."
"This game sounds very much like what I do already," noticed the Doctor.
"Then you should be very good at it," Toggle reasoned.
"What is the point of this?" he demanded.
"I already told you: the object is to—"
"For you: what is the point for you?" the Doctor interrupted.
"What's the point of any game?" she retorted. "If you win I'll take you back here, return your TARDIS key, and never bother you again. If you lose I'll remotely detonate your vortex manipulator and strand you in whatever world you fail to save. If you attempt to break any of the rules or disobey any of my commands you forfeit the game. Understand?"
"No," the Doctor said. "The universe has enough dangers without you fabricating more for your own amusement. And what's more, you shouldn't even exist. You're made of void-stuff. How is that possible?"
"You cheat death by magically turning into another person with the same memories: how is that possible?" Toggle retorted crossly. "Enough chat: time to play. Round one will be played here."
"Here? Have you triggered another bomb?" Kate wanted to know.
"No: the first one served its purpose," Toggle said. "Now then, Doctor, can you save them?"
"What purpose? What did you do?" the Doctor demanded.
"Sorry, I probably should have mentioned: when I ask 'can you save them?' it marks the beginning of the round," said Toggle. "No more hints until Round Two. Good luck."
"What was in that lab?" the Doctor asked Kate.
"Bio-research," Kate told him. "We use it to study any biological residue on alien technology that we acquire, and in some cases recreate it. It's mostly dead skin cells and the like, but it's led to the development of several medicines."
"What are you working on now?" he asked. "Do you have anything new? Anything important that someone would want to destroy?"
"No, nothing recent," said Kate. "And whatever new developments she destroyed: we've gotten on fine without them so far."
"What exactly did she destroy?"
"Here's a catalog of the damage," she said, handing him a folder.
"No…no…damaging, but not dangerous…no," said the Doctor, leafing through it. "You managed to isolate the genes that create electrical pulses from Slitheen DNA? Well done, Kate. But there's nothing in here that could be perilous. Unless…hang on! That cooling tower there: what was it for?"
"It keeps the storage container refrigerated."
"And what's in there?"
"At the moment? I'm not sure," Kate said. She logged into the computer and pulls up a database. "Everything should be logged…there!" The Doctor scans through the data faster than Kate can read it.
"That's it," he said finally, running a hand through his hair anxiously.
"What's it?" asked Kate.
"Asphrodinium," said the Doctor, pointing at a chemical formula that was labeled 'BacteriaB578'.
"What is it?"
"Bacteria from the planet Trobelime," he said. "Airborne, dormant if kept at a temperature under 3.3 °C, and lethal to most carbon-based lifeforms."
"Undoubtedly," said the Doctor. "And given the time of the explosion…I'd say we've got about four minutes before those with the most exposure start showing symptoms, thirty-six before people start dying."
"Set up quarantine around the entire facility," Kate said into her walkie-talkie. "Complete lockdown: not so much as a molecule of air gets out. Over." To the Doctor she asked, "Is there a cure?"
"Yeah there's a cure, but not enough time to develop it," the Doctor said. "Unless you have some of the components already made! I need to use your lab."
"The bacteria will have contaminated the whole lab by now," Kate protested.
"Yeah, but I'll be fine: at worst asphrodinium will give me a stomach ache," the Doctor assured her. "In the meantime, gather everyone together and blast the air conditioning. Fill the room with ice, do whatever you can to keep their temperatures down. The first stage is rising core temperatures."
"What are the other stages?" asked Kate.
"Organ failure caused by the high internal temperatures, then death," he said. "But don't worry because we're going to cure them before that happens." With that, he ran off to the bio-research lab.
The Doctor was busy titrating a solution when a young man marched into the lab and donned a lab coat.
"You shouldn't be in here," said the Doctor, not taking his eyes off the slowly forming droplets.
"I work here," the man argued. "Collins is my name: Dr. Richard Collins."
"Well I don't know if you noticed, Dr. Collins, but we're in a bit of a lockdown," the Doctor replies.
"I know, sir," said Collins. "And everyone in here has been poisoned by asphrodinium…whatever that is. I can help you: I know where everything is and how it works. Just tell me what you need." The Doctor looked at him for the first time. Collins was in his early thirties at most.
"The bacteria are at their strongest concentration here," he explained gently. "The longer you stay here the less likely it is you'll be able to leave."
"Yeah, and how are you going to mix up a cure all by yourself in half an hour?" Collins retorted.
"I'll think of something," reasoned the Doctor.
"Oh, alright," the Doctor conceded. "See if you can throw together a mixture of two parts acetomenaphane, one part hydrogen-sulfate, and four parts water. Heat it to boiling, then titrate it into this beaker here."
The two worked in relative silence for a while.
"I've heard all about you, you know," Collins said after a time. "You're something of a legend around here."
"May I just say, it's an honor to work with you, sir," said Collins, wiping sweat from his brow. The Doctor looked him over with sad eyes.
"Likewise," he said.
"Miss Stewart said you talked to the bomber," Collins continued. "Do you know why she did it?"
"Not yet, but I'm working it out," the Doctor said, grinding an assortment of pills together. "I've met someone like her before…long time ago. Well, not like her exactly, but he set up the same kind of 'games'. Celestial Toymaker, he was called."
"Do you think she works for him?" asked Collins.
"Maybe, but I don't think so," he mused. "He was an eternal who'd set up whole worlds to stage his games, while Toggle is intrinsically part of hers. There's something else too: something I'm missing. Like she's not quite enthusiastic enough. I've known people—quite a lot of people—who hurt others because they enjoy it; and then there are those who do it to achieve some goal. She doesn't seem quite mad enough to enjoy it, but why call it a game if it's not supposed to be fun?"
The Doctor stopped talking when Collins collapsed. The Doctor rushed over to him.
"I'm fine: I'm alright," Collins insisted, using the table to pull himself to his feet. "Just felt a bit woozy for a moment there." The Doctor scanned him with his sonic screwdriver.
"You may want to step outside for a bit," suggested the Doctor. "Your temperature is a bit high."
"A bit, yeah," chuckled Collins. "Look, Doctor, we both know time's running out for everyone; and you're not going to finish in time without me. Least I can do is make myself useful."
The Doctor opened his mouth to say something, but thought better of it. They both returned to work as the seconds ticked by. Six minutes later, Collins began to cough up blood. The Doctor ran over, and helped him gently to the floor.
"Hang in there," urged the Doctor. "Pretty soon we'll have the cure and you'll be fine." Collins tried to laugh, but instead spit out some more blood. One of the solutions behind them reached a boil. "Back in a moment," said the Doctor, rushing over to lower the heat. Then he was back at Collins' side.
"We saved everyone, didn't we?" Collins asked. "It'll be done in time?"
"Yes, definitely," said the Doctor. "Two more minutes and we can start distributing it. Oi, Collins! Stay with me," he said, shaking him slightly to bring his eyes back into focus. "Couldn't have done it without you, you know," the Doctor continued. "And you're gonna help me cure the others, just as soon as I've cured you. You just need to stay with me. Come on, Richard: just fifty seconds longer."
"Tell Mariam…" Collins said. He passed away before he could finish. The Doctor closed his eyes tightly.
An alarm dinged. The Doctor leapt to his feet and pulled the test tube out of the centrifuge. He carefully poured it into the simmering beaker and waved away the resulting smoke. Then he distributed the liquid into twenty test tubes and corked them. Gathering the tubes and syringes, the Doctor ran out of the lab.
Soldiers and scientists were lining the halls. Some were coughing blood, some were curled up and moaning, and some had already passed on. The Doctor kneeled beside the first one, filled a syringe from one of the test tubes, and injected it into her arm. He'd injected nine people by the time the first woman was able to get to her feet.
"Here," he said, handing her a bundle of syringes and one of the test tubes. "Start injecting this into the others. Quick as you can."
Fifteen minutes later the quarantine was lifted. There had been very few casualties, considering, and the survivors would be fine after a few days' rest and standard medical attention.
"I don't know that we can ever thank you enough," said Kate.
"Dr. Collins, he mentioned a woman: Mariam," the Doctor said.
"That's his wife's name," Kate told him.
"She should know that everyone here would be dead if it weren't for him," he said.
"I'll make sure she knows; and that she's well cared for," Kate promised.
"Well done, Doctor," said Toggle through the communicator. "By the way, your garbage disposal is a bit clogged: you may want to look into that." The Doctor grimaced.
"Sometimes you flicker into sight: why is that?" asked the Doctor.
"Nature of my being I suppose," Toggle said thoughtfully. "Ready for Round Two?"
"You're not cross with me," the Doctor observed. "Before, you got cross with me when I asked about you; but not this time. It's as if you're happy that I won the round: why is that? Why put people in danger if you want them to be saved?"
Instead of replying, Toggle pressed a button on her remote control, and the Doctor was teleported to another planet and time. The wind was fierce. Dust and small rocks were blowing past him and being sucked up into the sky.
"Where am I?" he asked.
"Look up," said Toggle.
"I'm trying," he said, shielding his eyes as best he could from the dust storm. "What's happening? Is the planet being sucked into a black hole?"
"Not a black hole, per say, but that's the basic gist," Toggle told him.
"How do you expect me to stop that?" the Doctor asked.
"You're clever: figure it out," she suggested.
"There were good people in that lab, and you murdered them," said the Doctor.
"There are people on this planet too: can you save them?"
"I'm sorry, what?" asked Toggle.
"No," he repeated sadly. "I'm sorry, but this is a fixed point in time."
"Oh no, we're not playing that game," Toggle said with mild annoyance. "Just play the game and I'll return your TARDIS to you, simple as that. There's nothing to be gained by trying to outsmart me."
"I'm not trying to outsmart you," the Doctor told her. "I'm telling you this planet can't be saved. It's a fixed point in time: I can't interfere with fixed points."
"Then you can say goodbye to traveling the universe, because I'll never give you back your TARDIS," Toggle snapped.
"Pick another planet if you're so desperate to play," the Doctor suggested.
"That's not how this works," Toggle shouted. "I pick the playing ground, and you save the people!"
"Not this time."
"You have to!" Toggle screamed. There was a long pause.
"Why?" asked the Doctor.
"'Why?'?!" Toggle repeated.
"What's so important about this particular planet?" he asked. Then he paused and looked around. "Hang on. You said there are people here, so where are they?" And suddenly he realized. "Oh."
"'Oh'?" prompted Toggle.
The Doctor pulled out his 3-D glasses and put them on. Beneath the topsoil the whole planet was made of void-stuff. More importantly, the whole place was bursting with people. They were all made of void-stuff and milling around what appeared to be some kind of void-stuff marketplace. He spun in a slow circle, taking it all in. There was a whole civilization there—houses, vehicles, families—all invisible to the naked eye.
"This is your planet," he said. "Is that what this is all about? You want me to save your planet. But why the elaborate game? Why put other people in danger?"
"I was told I'd need to draw you in: give you something dangerous and complex," she replied.
"Told by whom?" he asked. "And anyways, why have three rounds if only the second round matters?"
Toggle answered his questions, but the Doctor didn't listen. The wind had died down a bit and the dust cleared, so when the Doctor happened to glance up he got a clear view of the sky and his hearts skipped several beats. He took off the 3-D glasses just to make sure.
"Hello?" Toggle was saying repeatedly. She used her own vortex manipulator to teleport beside him. "Why are you staring at the sky?" she wondered, following his gaze.
"I know where I am," he said. "I'm in the constellation of Kasterborous, at galactic coordinates 10-0-11-0-0 by 0-2 from Galactic Zero Centre."
"…yeah," said Toggle slowly. "How did you work that out?"
"I grew up under those constellations," said the Doctor. "This is the space that Gallifrey used to occupy."
"Until it was taken out of time," Toggle finished.
"How can there be a planet here?" the Doctor asked.
"When Gallifrey was taken out of time it left a sort of hole in the universe: an empty space that should be filled with something," explained Toggle. "Then came the daleks."
"No, the daleks came before that," the Doctor interrupted. "They were part of the Time War."
"Right, but what I meant was the daleks built a reality bomb in several universes," said Toggle, "and the barriers between the universes began to fracture. The void began leaking into the universes."
"The void can't leak into things: the void is nothing," protested the Doctor. "That means things leak into the void, not the other way around."
"You're covered in what you call void-stuff," Toggle pointed out, "so you know there's something there. It just can't be fully perceived by uni-dimensional beings. When the reality bomb was averted in this universe, most of the void-stuff was sucked back into the void. But some of it collected here. Planets aren't supposed to be removed from time: this space still needed to contain something. So the void-stuff filled the hole: it formed a planet here."
The wind picked up again, so Doctor put his 3-D glasses back on. Along with the dust, a steady stream of void-stuff was swirling up into the Untempered Schism. And it burned up as it entered the Time Vortex unshielded.
"Void-stuff doesn't occupy real space. Without a hold on the fabric of space-time, it's getting sucked into the Time Vortex," he realized.
"But you can stop it?" asked Toggle.
"Toggle, I'm sorry, I truly am, but this is fixed: there's nothing I can do,"
"Of course there is: you're the Doctor," Toggle insisted. "You save everyone. You said it yourself: that's what you do. Maybe what I did was wrong—we can argue about that later—but these people are innocent. Save them. Please."
"Some time can be altered, and some of it can't," explained the Doctor. "There are some events that have to happen—that always happen—and there's nothing I or anyone else can do to stop it. If you try to stop it then all reality would just fall apart. Toggle, I'm sorry, but this is one of those times."
"No one here is flickering into visibility like you do," the Doctor observed. "Why is that?"
"Tell me why!" Toggle demanded.
"I'm trying to," replied the Doctor. "Flickering: what's that about?"
"I wanted to see the universe," she said. "I got ahold of a vortex manipulator and started traveling through time. That's when it started: I can't walk through walls anymore and people can hear and sometimes see me.
"Is that what protected me? So, if we took everyone here through time, would they become like me and not get sucked into the vortex? We could use the TARDIS: the whole planet could easily fit in there!"
"Protected you? You mean this already happened?" he asked sharply.
"Everything already happened, Doctor, depending on your perspective," Toggle pointed out.
"To you though," he said. "This planet fell into the Untempered Schism during your timeline."
"I wasn't here when it happened," she told him. "But neither were a lot of other people. I was with some of them, and when the planet got sucked in all the way they went with it."
"It took billions of years to absorb the planet and once that was gone all that powerful suction swept everyone up in no time," the Doctor reasoned.
"…okay, sure," Toggle agreed. "Anyways, I came home to look for them and it was just gone," she continued, voice breaking slightly. "I worked out what had happened, and then I heard about you and I thought…"
"That's why it's fixed," he realized. "You're trying to change your own past, but once you've lived it you can't go back."
"You went back in time and found me because of what you saw in the future; if we prevent that future from happening—"
"There'd be no reason for me to look for you in the first place," Toggle finished for him.
"Paradox," he concluded. "Toggle—" he began, but she pressed a button on her vortex manipulator and vanished. "Toggle," the Doctor repeated more harshly into the communicator. Nothing but static came through from the other end. He sonic-ed his vortex manipulator and it teleported him back to UNIT moments after an earlier version of the Doctor had left for Round Two of the game.
He found Toggle leaning against the TARDIS with her knees pulled to her chest, crying. The Doctor stepped towards her, and she flung the TARDIS key at him. He picked it up and tried to think of something to say.
"You could have left at any time," she realized. "Why didn't you?"
"You were sending me where people needed my help," the Doctor pointed out. "And anyways you had my TARDIS captive so I thought I'd play along.
"Are you okay?"
"No," said Toggle. The Doctor sat beside her and put an arm around her shoulders.
"It gets easier with time," he assured her.
"Is that a lie?" she asked.
"Bit of a lie, yeah," he admitted.
"There's really no way to save them?"
"There's really not."
"How do you know?" Toggle wondered.
"The same way I know there's no way to save my people," said the Doctor. Toggle nodded. It was an assertion that was hard to argue against.
"As points in space go that one must be really unlucky," she said, wiping her eyes.
"Nah, I don't believe in luck."
"Me neither," she admitted.
"You alright now?" he asked. Toggle forced a smile.
"I'm always alright," she said.