Chapter Eleven: Make New Friends, But Keep the Old

The trip to Anguin was the start of a series of firsts for Donna. First alien beach, followed by her first trip to the infirmary to treat her sunburn. First palace uprising, first time thrown in jail, first time visiting a place no humans had ever been before…

Rose studied her one morning as they gathered in the console room. There was a smile on her face, but more importantly, there was a glimmer of confidence in her eyes that hadn't been there a month ago.

Time to put her in the driver's seat. "Donna Noble," she said, gesturing expansively. "What would you like to do today?"

Donna snorted and pointed from Rose to the Doctor. "Do you know how much you sound like him sometimes?"

"Oi!" The Doctor sniffed and adjusted the knot on his burgundy tie. "I don't know why you say that like it's a bad thing."

"Maybe not all the time, Spaceman, but we really only need one over-the-top alien on this ship."

Rose laughed when the Doctor frowned and rubbed at his eyebrow. He couldn't decide if he should be offended on his behalf or hers, and his consternation was endearing.

"Well, Donna," she said, "I'm afraid you're going to have to put up with two over-the-top aliens. But that doesn't answer my question. What do you want to do today?"

Donna leaned back against the railing and looked at the ceiling for a few minutes before straightening up, a broad grin on her face. "I want to learn how to fly the TARDIS."

Rose blinked. That was certainly another first, but she hadn't expected the request. Martha had been with them for nearly a year when they'd started to give lessons, and Donna had only been with them for a little over a month.

The Doctor spoke up before she got over her surprise. "All right then," he said readily. "We can give you a few beginner lessons at least."

"I think I'll just sit here and watch," Rose said, taking a seat on the jump seat.

Donna frowned. "But you're a better pilot than him."

Rose nodded. "And he's got hundreds of years experience in teaching people how to fly her. Knowing how to do something is way different from knowing how to teach someone else to do it."

Donna looked a little less certain, and Rose smiled reassuringly. "If it makes you feel better, Donna, he taught me. At least… until the TARDIS took over."

"Not sure that helps, but thanks." Donna took a deep breath, then looked at the Doctor. "I'm ready."

The Doctor took a circuit of the console, adjusting a few dials as he went. "All right. The very first thing I'm going to teach you is how to move through the Time Vortex. That's where we are right now."

"What is the Vortex?" Donna asked.

"Too complicated to explain to someone who doesn't have an advanced understanding of temporal mechanics," the Doctor said.

Rose cleared her throat and shook her head when the Doctor looked up at her. He shrugged and gestured, as if to say, If you'd like to explain…

She nodded sharply, then smiled at Donna. "The Time Vortex is the fifth dimension, Donna. It's a physical space that encompasses time. Picture it… like King's Cross Station."

The Doctor snorted softly. "Been reading Harry Potter again, Rose?"

"Oi! It works." She looked at Donna again. "So, there are twelve platforms at King's Cross, right? Plus, from there you can get to almost every line on the Tube."

Donna nodded slowly. "So the Vortex is like a hub."

The Doctor rocked back on his heels and tugged on his ear. "I take it back, Rose—that's a rather brilliant analogy."

Rose preened. "Why thank you."

He smiled at her, then looked back at Donna. "So, following that explanation, what we do when we're ready to leave the Vortex is navigate through it until we find the right platform. That's the part I want to teach you today."

Donna laced her fingers together and stretched them out. "All right then, what do we do first?"

The Doctor beckoned to her. "Come stand over here," he said. "Put your left hand on this lever, and your right on that pump." He pointed to the controls he wanted her to work, then raised an eyebrow at Rose. "Sure you don't want to help?"

Rose sighed theatrically, but jumped off the seat. "You don't really need my help," she said, "but since you asked, I'll take the hand brake off for you so she's floating free in the Vortex."

The hand brake was a small lever on the opposite side of the console from the dematerialisation lever. Rose had often wondered why exactly the ship had configured the controls in such an inconvenient fashion, but the only answer she'd gotten was that TARDISes weren't meant to be piloted alone.

The time rotor started its slow up-and-down chug as soon as the hand brake was released. The Doctor nodded and took a breath. "All right, Donna, the two controls you've got are for time. The lever sends us forward or backward. Which way do you want to go?"

Donna slowly moved the lever, and Rose felt them shift in the Vortex.

"That's it," the Doctor encouraged. "Now, the pump controls our velocity. Do you want to get where we're going a bit faster? Pump it a bit harder."

Donna kept up a slow pump on the throttle and watched the time rotor with glowing eyes. "I can't believe I'm doing this!"

"No, neither can I," the Doctor muttered.

Rose poked him in the ribs, but he didn't have a chance to defend himself before he had to go running around the console as Donna jerked her lever.

"Oh, careful." He grabbed the mallet he still kept on the console, despite all of Rose's best efforts to convince him to put it away. He hit one control and pulled a lever, then stepped back to let Donna take control again.

"Left hand down," he instructed, repeating the instruction more vehemently when she didn't comply quickly enough. "Left hand down!"

Donna pushed the lever down hard, and the TARDIS made a shuddering noise as she shifted abruptly. They all wobbled on their feet for a moment in the brief temporal turbulence.

The Doctor grabbed Donna's arm, keeping them both upright. "Getting a bit too close to the 1980s."

A scowl pinched Donna's face into sharp lines. "What am I going to do, put a dent in them?"

Rose watched the Doctor take a deep breath, and she knew he was about ready to launch into lecture mode at top speed. She pressed her lips together to hide her smile and leaned against the railing to watch him in his element.

"You could—because here's where the King's Cross analogy breaks down. The TARDIS isn't a passenger looking for a train. She's an incredibly powerful time machine, barreling into the station herself. Too fast or too hard, and you can cause serious damage."

Before Donna could come back with a witty retort, the muffled sound of a mobile ringing echoed in the console room. Rose frowned and reached into her jeans pocket for her phone. She took a peek at the caller ID before answering, and a wide smile spread across her face. "Hi, Martha."

"Rose?" Martha sounded exactly like she remembered. "Oh, I've missed you. I need you and the Doctor back on Earth."

"Oh, brilliant," Rose said. "Here, I'll let you give the coordinates to the Doctor." She handed the phone over, saying, "Martha needs us on Earth."

He nodded and took the phone. "Martha? Where are you?" He listened, adjusting the spatial coordinates as she talked. "And when? February 5th, 2009 at 0900?"

"Excuse me, Donna," Rose said, shifting in front of her to set the temporal coordinates. "It sounds like we've got someplace to be."

"Excellent," the Doctor said. "We'll see you in just a minute, Martha Jones. Don't you go anywhere."

He tossed Rose's phone back to her, then grinned at her and Donna and flipped the lever that would send them into flight. "Allons-y!"

The TARDIS rocked into flight, and they all clung to the console as they flew through the Vortex. "Martha's the one you travelled with before, yeah?" Donna asked.

Rose nodded. "She's a medical student, or was when we met her. If it's February now, it's been nine months since we dropped her off at home. She might have finished her exams finally."

The TARDIS landed with a slight hop and a bump, and Rose was out the door before they'd even settled. Martha stood at the end of the alley, a broad smile on her face that matched the one Rose could feel stretching her cheeks.

She took one step away from the TARDIS and Martha mirrored her, then they ran to hug each other. "Oh, it's good to see you," Martha exclaimed. She pulled back and grabbed Rose's hands. "Let's not go nine months without even talking again, all right?"

Rose glanced over Martha's shoulder, and her friend squeezed her hands. "Hang on. How long has it been for you?"

"A little over a year," Rose admitted.

Martha blinked, then she nodded approvingly. "Good! I'm glad you took some time off."

The TARDIS doors opened, and the Doctor's coat brushed against Rose's legs as he strode past her to sweep Martha up in a hug of his own. "Martha Jones," he said exuberantly once he released her.

"Doctor."

The Doctor stepped back and looked Martha over with a critical eye. "You haven't changed a bit," he pronounced after a moment. Shadows still lingered in her eyes, but they weren't prominent like they had been before—only someone who knew to look for them would find them.

"Neither have you." Martha glanced back at Rose. "You look good, both of you. Rose said it's been a year?"

The Doctor nodded.

"A year for a year," she mused, and he wasn't surprised she put that together so quickly.

Martha's gaze shifted to his right, and the Doctor turned slightly to include Donna in the conversation. Martha smiled and held her hand out. "You must be the new companion. I'm Martha—Martha Jones."

Donna smiled warmly and shook her hand. "Donna Noble. Lovely to meet someone else mad enough to travel with these two."

"Oi!" the Doctor and Rose protested in unison.

"Oh, I like you, Donna," Martha said, a grin on her face.

"So, Martha," the Doctor said, raising his voice a little to redirect the conversation. "We were wondering on our way here if you'd taken your exams yet."

To his surprise, a secretive smile flitted across her face. "Not exactly," she said mysteriously.

Before he could ask what that meant, the walkie-talkie on her hip buzzed. "Dr. Jones, report to base, please. Over."

Martha took the walkie-talkie and brought it to her mouth. "This is Dr. Jones," she said as she spun around and led the way out of the alley. "Operation Blue Sky is go, go, go. I repeat, this is a go."

The Doctor and Rose looked at each other as they followed Martha, then shrugged when they realised the other was just as baffled by Martha's sudden change in demeanour as they were.

A moment later, when they stood on the edge of the street and watched the convoy of UNIT vehicles make their way into the ATMOS factory, Martha's behaviour made some sense. The Doctor's eyebrows rose when a Jeep drove past them, carrying a colonel. This Operation Blue Sky, whatever that was, obviously was important to UNIT brass if a colonel was in charge.

But at the moment, he was more interested in the changes in Martha. He'd seen her stand with this military bearing before, and once he placed the memory, a knot of guilt in his gut. She'd looked like this when she'd faced down the Master. It was something she'd learned during the Year That Never Was.

Rose took his hand and brushed her thumb over his knuckles, and the Doctor relaxed at the unspoken reminder. It wasn't his fault.

"Greyhound Six to Trap One," Martha said into the walkie-talkie. "B Section, go, go, go. Search the ground floor. Grid pattern delta."

"What are you searching for?" the Doctor asked as they followed the vehicles on foot.

"Illegal aliens."

"This is a UNIT operation," a voice announced over a loudspeaker. "All workers lay down your tools and surrender immediately."

As Martha ran towards the building, shouting more orders into her walkie-talkie, the Doctor watched uniformed UNIT officers pull blue collar workers out of the factory and push them to the ground. His lips curled in a snarl. No one was using unnecessary force, but it was clear the workers were confused and frightened.

He was just considering who he might talk to about treating people with more respect when Martha walked back to them, her stride confident and purposeful. It was jarring to see the young woman who'd wanted to do nothing more than help people look so at home in the middle of a military operation.

Yeah, it is, Rose agreed. But let's talk to her and find out why she's working for UNIT, she suggested.

The Doctor looked down at her name badge and noticed something he'd just barely caught when they'd called her earlier.

"You're qualified now. You're a proper doctor."

"Oh, that's brilliant," Rose said.

Martha smiled and pushed her hair back over her ear. "UNIT rushed it through, given… well, my experience in the field." She shrugged and looked away for a moment, then motioned for them to follow her. "Here we go," she said as they walked across the street to the command unit on wheels he'd watched roll by earlier. "We're establishing a field base on site. They're dying to meet you."

"Wish I could say the same," the Doctor muttered. He could already tell the Brigadier wasn't in charge of this particular mission, and he'd never gotten on well with any of UNIT's other commanders.

Be polite, Rose reminded him, and he pressed his lips into a thin line.

Martha either didn't hear his sarcastic comment, or she chose to ignore it. She marched proudly into the mobile base and approached the same colonel the Doctor had spotted earlier. "Operation Blue Sky complete, sir. Thanks for letting me take the lead. And, this is the Doctor and Rose Tyler. Doctor, Rose; Colonel Mace."

"Sir, Ma'am." Colonel Mace snapped to attention and saluted.

"Oh, don't salute," the Doctor whined.

Colonel Mace tilted his head. "But it's an honour, sir. I've read all the files on you." He looked at Rose first. "The Brigadier was very impressed when he met you, ma'am. Said you were the perfect partner for the Doctor. 'The only one who can keep up with him, and rein in his more harebrained schemes,' I believe were the exact words he used."

The Doctor was torn between indignation over the characterisation of his adventures, amusement at his old friend's words, and pride in Rose. In the end, he settled for rolling his eyes, just as Colonel Mace looked back at him.

"And you, Doctor." The man smirked. "Technically speaking, you're still on staff. You never resigned."

Donna's eyes widened and she looked up at the Doctor. "What, you used to work for them?"

"Yeah, long time ago," he admitted reluctantly. "Back in the 70's. Or was it the 80's?" He stood on his toes and looked over the colonel's shoulder at the bank of computers lining one side of the small room. "But it was all a bit more homespun back then."

"Times have changed, sir," Colonel Mace said tactfully.

The whole military demeanour, including the constant use of "sir" and salutes, had just about robbed the Doctor of what was left of his patience. He opened his mouth to snarl at them, but Rose squeezed his hand gently, and instead, he took a deep breath and let her speak.

"There's really no need to call the Doctor sir, Colonel," she said smoothly. "I'm sure the Brig told you we don't like to stand on ceremony. Our names are fine—the Doctor and Rose."

He hesitated a moment, then nodded slowly. "Sir Alistair did say something along those lines," he admitted. "Something about… the Doctor not appreciating all the military folderol."

Rose's humour brightened the Doctor's mood. "That's a fairly accurate representation," she agreed.

The Doctor squeezed Rose's hand in thanks. It seems the Brig was also right about you reining me in. Thank you, Rose.

He looked back at the tech support officers, hard at work on the computer terminals. The entire wall over their heads was a series of computer displays, each displaying different readouts.

"This is definitely different from what I remember," he admitted.

Martha led them to one bank of computers. "We've got massive funding from the United Nations, all in the name of Homeworld Security."

"A modern UNIT for the modern world," Colonel Mace said proudly.

Watching from the sidelines—nearly ignored by everyone—Donna rolled her eyes. The military egos in this room were unbelievable. It had been on the tip of her tongue earlier to ask the Doctor if he turned his companions into soldiers, but she'd remembered Rose's warning to not guilt trip him for things just in time.

But the attitude in this room was too much. Donna snorted, and the colonel turned to her, surprise and confusion on his face. Well, she'd tell him what she was thinking, soon enough. "What, and that means arresting ordinary factory workers, in the streets, in broad daylight?" She pointed towards the outdoors. "It's more like Guantanamo Bay out there. Donna, by the way," she added, taking pleasure in the man's baffled expression. "Donna Noble, since you didn't ask. I'll have a salute." She might not have worked for UNIT since the 70s or 80s, but she still deserved respect.

The colonel turned to the Doctor and Rose, who both nodded, Rose while trying to hide a smile. The military man sighed as he turned back to her, but gave a sharp salute. "Ma'am."

"Thank you."

They all turned to look at the largest monitor, which displayed a map of the timezones of the world. The Doctor slid into an empty chair at the end of one table, and Rose stood behind him with her hand resting on his shoulder.

"Tell me," the Doctor invited, "what's going on in that factory?"

Colonel Mace nodded at the map. "Yesterday, fifty-two people died in identical circumstances, right across the world, in eleven different time zones. Five a.m. in the UK, six a.m. in France, eight a.m. in Moscow, one p.m. in China."

Rose sucked in a breath. "They died at the same time."

"Exactly," the Colonel said. "Fifty-two deaths at the exact same moment, worldwide."

The Doctor leaned forward and rested his chin on his fist, staring at the map. "How did they die?"

"They were all inside their cars," said the Colonel.

"They were poisoned," Martha elaborated. The Doctor sat up and looked at her. "I checked the biopsies. No toxins. Whatever it is left the system immediately."

"What have the cars got in common?" the Doctor asked.

Martha shook her head. "Completely different makes. They're all fitted with ATMOS, and that is the ATMOS factory," she concluded, tilting her head towards the military action going on outside.

Rose's ponytail swished when she turned to look at Martha, a wrinkle between her eyebrows. "What's ATMOS?"

Donna rolled her eyes. The entire conversation had left her feeling completely out of her depth, but at least she knew the answer to that. "Oh, come on. Even I know that. Everyone's got ATMOS."

Rose looked at her. "We don't exactly have a car," she said, like it was the most obvious thing in the world.

Martha chuckled. "You know, I'd forgotten how much you could sound like him sometimes."

Donna had flinched at Rose's tone, but she straightened up now and grinned at Martha. "Oh, I told her that just this morning! Finally, someone else who can see it, too."

"All right!" The Doctor held up his hand. "I won't ask—again—what's so bad about sounding like me. Instead, I'll just point out that so far, no one has actually answered our question about what ATMOS is. It seems like this is a bit time sensitive, if anyone would like to get on that?"

Martha rolled her eyes. "Yes, sir," she muttered. "Come with me."

Colonel Mace's hand spasmed as they walked out, and Donna nudged the Doctor once they were outside. "What's so wrong with getting a salute?" she asked. "You've got that colonel all twitchy."

The Doctor shoved his hands into his pockets as they followed Martha across the compound into the main part of the factory. "They tend to forget that I'm not actually military—don't even really like military. Refusing all the military folderol, as the Brig put it, is a reminder."

They took the lift to the upper level as soon as they were inside, and Donna frowned at the activity on the factory floor. Uniformed soldiers were leading people out of the building, their hands over their heads.

"ATMOS stands for Atmospheric Emission System," Martha explained as they walked. "Fit ATMOS in your car, it reduces CO2 emissions to zero."

"Zero?" the Doctor repeated, shocked. "No carbon, none at all?"

"And you get SatNav thrown in, plus twenty quid in shopping vouchers if you introduce a friend," Donna added. "Bargain."

Ahead of them, Colonel Mace stopped and gestured down at the factory. "And this is where they make it, Doctor. Shipping worldwide. Seventeen factories across the globe, but this is the central depot, sending ATMOS to every country on Earth."

"And you think ATMOS is alien," Rose concluded.

Colonel Mace smiled tightly. "It's our job to investigate that possibility. Doctor?"

The Doctor stared down at the factory for a moment before following Colonel Mace and the others down the stairs. Donna's comparison to Guantanamo Bay was unnervingly accurate. And it only got worse when they were on the ground floor and he could actually see the scared faces of the men and women being herded out of the factory. Were it not for the mysterious, simultaneous deaths the day before, he would have demanded their immediate release. Instead, he vowed to solve the mystery as soon as possible so these people could be freed.

Colonel Mace led the way through a plastic strip curtain into a lab and pointed at a smallish device resting on the table. "And here it is, laid bare. ATMOS can be threaded through any and every make of car."

He picked up a model and the Doctor glanced down at it. "You must've checked it before it went on sale."

"We did," Martha assured him. "We found nothing. That's why I thought we needed an expert."

The Doctor pulled out his specs and slid them on. "Really. Who'd you get?"

A surge of amusement over the bond took him by surprise, and he looked at Rose, whose eyebrows were raised incredulously.

"Oh, right." He rubbed at his neck. "Me, yes. Good."

Martha shook her head and left the R&D lab, followed closely by Colonel Mace and the rest of the UNIT staff who'd joined them briefly.

The Doctor picked up one of the packaged models and turned it over, reading the description on the back. There was something… off about this whole concept.

"Okay. So why would aliens be so keen on cleaning up our atmosphere?" Donna asked, putting her finger on exactly the problem the Doctor had been trying to work out.

"A very good question," he said. "Any ideas, Rose?"

Her jaw was tight, and she shook her head. "I'd love to think they just want to help us get rid of pollution, but I keep coming back to those mysterious deaths."

"Exactly," the Doctor agreed. "There are eight hundred million cars on planet Earth. Imagine that. If you could control them, you'd have eight hundred million weapons."

He opened the box and pulled out the brand-new ATMOS device. "Let's see how this works." He took his sonic screwdriver out of his pocket and fiddled with the settings for a moment.

Donna sighed. "Look, this is your area," she said. "I'm going to go… see if I can find some other way to help. I'll be back."

The Doctor looked at her over the rim of his glasses. "Are you sure?" he asked.

She rolled her eyes. "What am I going to do? Wave my phone at it and see if it gives me mobile coverage? Nah, I'll find another way to get into trouble."

"That's what I'm afraid of," the Doctor muttered, grunting when she smacked his shoulder. "Just… don't wander off, all right? Stay nearby."

"Fine, Spaceman," she agreed, then left the tiny R&D lab.

"You're staying?" he asked Rose, without looking up at her.

She snorted. "As if I'd leave." She jumped up onto a counter and crossed her legs at the ankle. "I figure that while you scan that with the sonic, we can try to make sense of what we know so far."

The Doctor scanned the device, then turned and leaned against the table, his arms crossed over his chest. "All right. The sonic will beep when the results are ready. What are you thinking, Rose?"

Rose tapped her nails on the counter. "You used the word control a few minutes ago," she said. "You think that whoever is behind ATMOS has put some kind of hidden chip in the device that allows the vehicles to be controlled remotely."

"Fifty-two people died yesterday," he reminded her. "At the same moment."

"Oh, I'm not disagreeing," she said. "I just wanted to make sure I was following your train of thought."

Her mood shifted slightly, and he braced himself for her next question. "Now, why are you so on edge? Because that's got nothing to do with ATMOS."

The Doctor sighed and pinched the bridge of his nose where his specs rubbed. "I'm not a fan of the military; you know that."

"I do. I also know you've worked with and for UNIT before."

"Remotely, or with the Brig as my liaison," the Doctor countered. "I know the Brigadier. He's a military man, but he understands the importance of science and thinking things through first. I can count on him not to make rash decisions that put everyone at unnecessary risk."

Rose hesitated, and the Doctor raised an eyebrow. Why do you think it's so important that I'm courteous towards Colonel Mace? he asked, keeping this part of their conversation private from any listening ears.

Rose jumped down off the counter and walked over to him. Because if you antagonise him, he might not pay attention to you later when it's important that he listen. Plus, Martha seems to trust him, and I trust Martha.

The sonic screwdriver beeped before the Doctor could really work out all the angles of her argument and decide if he agreed with her. He read the results, then raised his eyebrows and turned around to look at the device.

"Oh really?" he muttered as he picked it up, turning it over in his hands.

Colonel Mace and Martha returned in time to hear that comment. "What did you discover, Doctor?" the colonel asked.

"Ionising nano-membrane carbon dioxide converter," he told them. "Which means that ATMOS works. Filters the CO2 at a molecular level." He whirled around and rested the ATMOS device on top of a Perspex model of a radiator, admiring the way it fit like it was designed to sit there.

Colonel Mace sighed impatiently. "We know all that, but what's its origin? Is it alien?"

"No. Decades ahead of its time."

The Doctor leaned over so he could look down the model tailpipe, visualising exactly what the ATMOS device did. Colonel Mace had followed him over to the model and loomed over his shoulder. The Doctor could see Mace's gun out of the corner of his eye, and several insulting, cutting remarks came to mind. He really didn't like guns, and he didn't like having one this close to either him or Rose. He looked up at her, and she smiled encouragingly.

He took a deep breath and straightened up. "So this, this ATMOS thing. Where'd it come from?" he asked as he grabbed it and scanned it again.

Colonel Mace nodded. "Luke Rattigan himself."

The Doctor looked at him over the rim of his glasses. "And himself would be?"

Colonel Mace blinked a few times. "As soon as we're done here, we can go back to HQ and I'll show you his profile. I can tell you that while his personality is a bit… grating at times, he's never given anyone in UNIT or the government reason to believe that he is anything other than what he seems."

The Doctor held up the ATMOS device. "Just like this didn't seem like anything other than a CO2 converter until it killed fifty-two people yesterday."

The Colonel stiffened and nodded sharply. "Point made, Doctor." He raised his hand halfway, then dropped his arm and spun around.

Rose sighed. "Well, that went better than it could have, at least."

The Doctor looked back at her. "What? I didn't say anything that wasn't absolutely true."

Martha huffed out a laugh. "You just implied that his intelligence operatives missed information so major, they'd let a threat to Homeworld security continue to walk free."

The Doctor sniffed. "Well, if he's so sensitive…"

Martha rolled her eyes. "He's a good man."

"He's military, Martha," the Doctor said, his voice flat. "His first instinct is to fight, when he should be trying to think of another way out of situations."

Martha shook her head. "It's all right for you. You can just come and go, but some of us have got to stay behind, deal with that clean-up that you always ignore. And sometimes, that means military action."

The Doctor finally asked the question that had been bothering him since he'd spotted the UNIT trucks. "How did you come to be working for UNIT anyway, Martha?"

Amusement glinted in Martha's eyes. "You got me the job, in a way. UNIT recruited me after reading over my debriefing from the year I walked the Earth." She tilted her head and looked at him. "I always thought you put in a good word for me, but I guess not."

The Doctor put the ATMOS device down. "Definitely not," he said adamantly. "I wouldn't even have thought you wanted to work someplace like UNIT. The last time we talked, you wanted to become a doctor and make the world a better place."

Martha squared her shoulders. "Well, maybe the first thing I make better is UNIT. But the only way I can change them is by working from the inside."

The Doctor smiled finally. "Yeah? That sounds more like you."

She grinned. "I learned from the best."

"Well."

Martha nudged his shoulder. "Yeah, I meant Rose."

Rose and Martha's laughter at his expense was interrupted by Donna pushing her way back through the plastic flaps. "Oi, you lot."

The Doctor blinked and looked up at her, standing with her hand on her hip and a binder in her hand.

"All your storm troopers and your sonics. You're rubbish." She shook her head, a tiny grin on her face, then walked towards them. "Should've come with me."

"Why, where have you been?" the Doctor asked.

Donna's smirk faltered slightly when Colonel Mace reentered the room, but she quickly reminded herself that she knew what she'd found was important.

"Personnel." She nodded smartly. As soon as she'd spotted the folder, she'd known. "That's where the weird stuff's happening, in the paperwork. Because I spent years working as a temp. I can find my way round an office blindfolded, and the first thing I noticed is an empty file."

"Why, what's inside it?" the Doctor asked, then quickly corrected himself. "Or what's not inside it?"

Everyone in the room was looking at Donna, but for once, she didn't feel like they were waiting for her to mess up. And she was right about this—she knew she was.

"Sick days," she explained. "There aren't any. Hundreds of people working here and no one's sick. Not one hangover, man flu, sneaky little shopping trip, nothing." It was gratifying to watch the shock and concern on their faces as they slowly realised what she was saying. "Not ever. They don't get ill."

The colonel stepped towards her and grabbed the empty file. "That can't be right," he insisted, opening the file and staring at it, as if it would suddenly be full once it was in his hands.

"You've been checking out the building." She tilted her chin up proudly. "Should've been checking out the workforce."

Martha Jones was the first to smile at her. "I can see why he likes you."

The praise from someone who barely knew her made Donna stand up straighter.

"You are good," Martha concluded.

"Super temp."

Colonel Mace nodded. "Dr. Jones, set up a medical post. Start examining the workers." He handed the empty file to Martha, then headed for the door. "I'll get them sent through."

"Come on, Donna," Martha invited. "Give me a hand."

Rose hopped off the counter as Donna and Martha left the room, and the Doctor beamed at her. "All right then, Rose Tyler." He snagged the ATMOS device in one hand and and took her hand with his other. "Allons-y!" They grinned at each other and ran after Colonel Mace.

They caught up with him halfway to the factory door. "Can you tell me more about this Luke Rattigan?" the Doctor asked.

The colonel nodded. "We can pull his file up when we reach the mobile HQ." He shot the Doctor a sidelong glance. "We have kept tabs on him, you know Doctor. You made it sound earlier like we'd just let someone… wander free, wreaking all kinds of havoc on the world."

The Doctor scratched at his sideburn. "I'm sure you have," he said, sincerely for once. "I just have a feeling that you've missed something. Because it all comes back to him, doesn't it?"

Colonel Mace pursed his lips, but nodded reluctantly. "You appear to be correct about that," he agreed as they stepped out into the sunshine.

The Doctor waited impatiently for them to pull up the file and get it projected on the screen, but then a weaselly face with a sharp chin and beady eyes appeared, and he straightened up.

"Child genius," Mace said, narrating the information onscreen, even though the Doctor could read it faster than he could talk. "Invented the Fountain Six search engine when he was twelve years old. Millionaire overnight. Now runs the Rattigan Academy. A private school, educating students handpicked from all over the world."

"A hothouse for geniuses. Wouldn't mind going there."

Rose put a hand to her chest and pouted. "Are you saying I'm not clever enough for you, Doctor?"

"No! Rose, you…"

Her bubbly humour caught up with him just a few seconds too late, and he let out a long breath of relief. "Not fair, Rose Tyler. That wasn't fair at all."

For the first time since they'd met him, Colonel Mace cracked a real smile. "I believe I understand what Sir Alistair meant when he said you were the Doctor's perfect match, ma'am."

oOoOoOoOo

Down in Human Resources, Martha immediately dug into the files. Donna watched for a moment, the rush of finding a mystery almost completely worn off, now that it seemed like she wasn't needed anymore.

At the same time, a thought that had been building in the back of her mind finally pushed its way forward. "Do you think I should warn my mum about the ATMOS in her car?"

"Better safe than sorry," Martha said briskly as she stood up.

Donna looked closely at the other woman. Martha was smiling, but along with the encouragement, there was something like wistfulness in her eyes. I wonder what she's thinking about, she thought, then said out loud,"I'll give her a call."

She was almost to the door when Martha called her back. "Donna. Do they know where you are? Your family. I mean, that you're travelling with the Doctor?

Donna frowned. "Not really." A memory returned, and a tiny smile crept across her face. "Although, my granddad sort of waved us off. I didn't have time to explain."

Martha nodded slightly, like that was the answer she'd expected. "You just left him behind?"

"Yeah." There was something in the words, in the way Martha said it, that sounded like an accusation, and guilt choked her. She hadn't even thought about her family since then, not until today, when they were back in London.

Martha sighed. "You need to tell them. At least let them know you're doing something that might be dangerous. I kept it from my family—thought it didn't matter, because I was going to come straight back on the same day I left, so why bother explaining that I'd been travelling? And…" She pressed her lips together, then nodded firmly. "Just tell them. Don't let them find out from someone else, or in the wrong way."

Donna stared at the other woman, a little unnerved. It wasn't that she hadn't considered it might be a good idea to let her family know she was off having an adventure; it was just… easier to not tell her mum. Even now, with the veiled warning from a previous companion, she shuddered at the thought of how Sylvia would react.

"I'm serious," Martha pressed. "Look, if you're not sure, ask Rose what happened the first time she came home. Believe me, you don't want something like that to happen."

oOoOoOoOo

Colonel Mace followed after the Doctor as they walked through the complex. "Doctor, I really think it would be wise of you to take an escort with you. If Luke Rattigan is involved, as you think he is…"

The Doctor shook his head. "I want to talk to this Luke Rattigan, not point a gun at him." He glanced up at the colonel. "No offence."

"None taken," he said, though his tight smile suggested otherwise. "It's ten miles outside London. How are you going to get there?"

"Well then, get me a Jeep," the Doctor suggested, waving at the vehicles nearby.

"According to the records you travel by TARDIS," the man countered.

"We do," Rose agreed, "but she's not really a London Hopper—she's more a long-haul vehicle. Plus, to be honest Colonel, if Luke Rattigan is involved in the mess here, I'd like to keep the TARDIS as far from him as possible." She wrinkled her nose. "I know too many geniuses. He'd probably try to take her apart."

Colonel Mace nodded. "Fair enough. However, if you're going to take a UNIT vehicle, you'll have to have at least one officer with you to drive. Is that acceptable?"

The Doctor nodded. "Yes, yes. Can we just hurry up? I have a feeling that time is of the essence."

The colonel held up his hand. "Jenkins?" he called.

"Sir." A private by one of the Jeeps looked up.

"You will accompany the Doctor and Miss Tyler, and take orders from them."

The Doctor opened his mouth to be difficult, but then snapped it shut when he remembered Rose's comment about wanting to have the colonel willing to listen to them when it became necessary.

Colonel Mace looked from the Doctor to Rose and back again. "Any sign of trouble, get Jenkins to declare a Code Red. And good luck, sir." He snapped a quick salute, then left before the Doctor could complain.

Good job, Doctor, Rose told him, taking his hand and squeezing.

"Doctor."

He spun around and ran towards Donna. "Oh, just in time." He grabbed her hand and started pulling her towards the Jeep. "Come on, come on, we're going to the country. Fresh air and geniuses, what more could you ask?"

Donna dug in her heels and forced them to stop. "I'm not coming with you."

The Doctor looked down at her and his hearts sank. She looked so… so homesick, so forlorn. This day always came—or usually, at least—but he'd expected more than a month with Donna.

"I've been thinking," she continued, saying the words he knew were coming. "I'm sorry. I'm going home."

"Really?"

Her eyes were downcast, and there were tiny lines around the corners of her mouth. "I've got to."

The Doctor nodded. He'd never keep anyone against their will, even if it hurt to watch them go. "Oh, if that's what you want. I mean, it's a bit soon. I had so many places I had wanted to take you. The Fifteenth Broken Moon of the Medusa Cascade, the Lightning Skies of Cotter Palluni's World…"

Laughter cut him off, and he looked over at Rose, leaning on a Jeep, one arm wrapped around her waist as she laughed, hard. He frowned; that wasn't the reaction he'd expected from her when their companions left.

And the penny dropped. He swallowed and looked back at Donna, feeling his face grow hot. "You're just popping home for a visit, that's what you mean."

She nodded, a wide smirk on her face. "You dumbo."

The Doctor tugged on his ear. "And then you're coming back."

"Know what you are? A great big outer space dunce."

"Yeah." The Doctor couldn't argue with that. Why had he thought Donna would be ready to leave so soon?

"Ready when you are, sir, ma'am."

The Doctor was glad of Private Jenkins' interruption, though looking at Rose and Donna, he didn't think either woman was going to let him live this down for a very long time.

Donna grinned at him. "What's more, you can give me a lift," she said as she jogged around to the other side of the Jeep. "Come on. Broken moon of what?" she asked as they climbed in.

"I haven't even been to all those places you listed, Doctor," Rose interjected.

"But I've taken you places I didn't mention," he protested. "How many places have we gone together, Rose Tyler?"

Rose tilted her head back and pretended to count as Ross started the Jeep and drove them out of the vehicle bay. "Oh, I think we were closing in on a thousand at the last count, weren't we?"

He wrapped an arm around her shoulders and pulled her close, so there was room for all of them in the backseat. "I think so."

Donna snorted. "I see you still cuddle together in the backseat of cars, just like you did last Christmas."

The Doctor rolled his eyes, and a puckish instinct stirred. Rose? Understanding his question, she turned slightly and tilted her head back as he leaned down. He bumped his nose against hers, then muffled her soft giggle with a kiss, starting a clock in his head as soon as their lips met.

Rose's lips curved up in a smile, then she adjusted the kiss so she had his lower lip between hers. The Doctor sighed when he felt her hand curve around the back of his neck to hold him close.

They'd only been kissing for twenty seconds when Donna groaned. "All right, you've made your point!" she grumbled loudly.

The Doctor eased out of the kiss, then smirked at Donna. "A little cuddle doesn't seem so bad now, does it?"

Donna pulled a face, then ignored him and looked at Rose. "Oh! Rose. Martha said I should ask you about your first visit home after you started travelling with the Doctor."

The Doctor felt any ground he'd gained disappear, and he groaned. "Before she answers, I want you to know that the TARDIS arranged that. It was all her idea."

Rose arched an eyebrow. "You'll have to explain that later," she said, then turned to Donna. "We'd gone on a few trips, been gone from home for maybe… two weeks?" She looked up at the Doctor, and he nodded. "And I thought it would be a good idea to go home, get some clothes, let my mum know that I'd be gone for a while. Because I'd already decided I wasn't going to go back until he made me."

The Doctor blinked; he'd never heard that part of the story. He watched Rose's cheeks turned pink as she caught his surprise and realised what she'd just given away.

"Anyway," she said hurriedly, "he took me back to London—said it had only been twelve hours."

"Oh, my God," Donna said. "How long had it really been? Twelve weeks?"

Rose shook her head. "Months, Donna. Twelve months."

Donna's jaw dropped. "A full year? He brought you home a full year late?"

Rose nodded and looked up at her. "My mum had missing posters up and everything. So if you're wondering if you should tell her, my advice is yes."

"Blimey! I didn't even think of that possibility." She nodded. "I'll think of something to tell her, then."

oOoOoOoOo

Martha sighed. Trading out the black leather jacket for her white lab coat had felt like she was getting back into her own skin for the first time all day. After nearly two years with the Doctor and Rose, she didn't think she could have gone to a typical hospital job—she was too used to the rush of adventure—but this part of her job was still what she liked best, when she got to actually care for patients.

A young ensign handed her a file when she reached the room they'd set up as an exam room. Martha glanced at it, then nodded and handed it back before walking into the room.

"I'm Dr. Jones," she said as she sat down across from the young man. Her hair fell into her face, and she immediately grabbed a barrette out of her pocket to secure it. "And your name's Trepper, yeah? Is that Polish? Listen, we're not checking passports," she assured him, realising a moment too late that her attempt at making conversation might scare an undocumented worker into staying quiet. "It's not about that. But did you come across from Poland just to work?"

Trepper didn't blink. "I came to do my job."

"Okay." Martha nodded slowly. "I need to listen to your heartbeat." She rubbed the bell of her stethoscope against her hand. "This might be a bit cold. Lift."

Still showing absolutely no affect at all, Trepper lifted his shirt. Martha pressed the stethoscope to his chest and had to work to keep her expression even; his heart was racing. "Are you on any medication?" she asked, thinking of a few that caused tachycardia.

"I'm here to work," Trepper recited.

Martha furrowed her brow. If he'd been overworked, if he was an undocumented alien who didn't know he had rights, the overwork could have affected his heart. "How many hours a day do you work?"

"Twenty-four," Trepper said in a flat voice.

Martha blinked; there was no way this man had been working twenty-four hours a day. He wouldn't still be standing if he had. "You work twenty-four hours a day?" she asked, then realised she hadn't told him he could put his shirt down. "Down."

Trepper obeyed automatically, and Martha got an inkling of what might be going on. She leaned forward in her seat and looked at the man, who still gave absolutely no reaction to her presence.

"Mr. Trepper, have you ever had any form of hypnosis?"

"I'm here to work," he repeated.

And that was enough for Martha. She nodded slowly, then got to her feet. "Okay. Er, if you could just wait here."

"I'll be right back," she told the officer standing outside the room. "Make sure he doesn't go anywhere, all right? He's not in trouble," she said quickly. "He just has information I think Colonel Mace will want to hear."

The young soldiers saluted quickly, and Martha started towards headquarters at a brisk pace. She was halfway there when she heard someone call her name behind her. When she glanced over her shoulder, she saw two soldiers, and she shook her head.

"Not now, I'm busy."

"Just one question," the taller one said. "Do you have security clearance level one?"

Martha stopped and frowned slightly. "Yes, I do. Why?"

"Colonel Mace wants to see you," he told her.

Well that makes things easy. "Oh good, because I want to see him. Where is he?"

"Come with us." They turned around and walked in the opposite direction she'd expected to find the colonel in.

Later, she'd be embarrassed to admit that she wasn't suspicious until they led her through an abandoned basement corridor. "What's he doing down here?" she asked, keeping her voice even while subtly glancing around for a way out.

"He asked to see you," the soldier repeated, definitively.

"Why?" Martha asked, now more curious than suspicious. "Has he found something?"

They opened a door and she strode through it, but instead of finding Colonel Mace, perhaps along with some of his higher ranking officers, she found an empty room filled with a pool of green slime.

She took a deep breath, then spun around and ran for the door, but the two soldiers were too strong. She was trapped.