Chapter Twelve: The Doctor Dances

"Go to your room," the Doctor said suddenly. Behind him, Rose and Jack shared a look, but it was working. The patients stopped in their tracks. "Go to your room. I mean it! I'm very, very angry with you. I'm very, very cross. Go to your room!"

Alex let out a sigh of relief as the patients shuffled back to their beds, hanging their heads in shame. "Oh, thank God."

"I'm really glad that worked," the Doctor admitted, glancing back at her. "Those would have been terrible last words."

Jack snorted, and they all relaxed, the threat over.

"So... why are they all wearing gas masks?" Rose asked, eyeing a nearby patient.

"They're not," Jack replied. "Those masks are flesh and bone." Alex wrinkled her nose.

"How was your con supposed to work, then?" the Doctor asked, raising an eyebrow.

"Simple enough, really." Jack shrugged. "Find some harmless piece of space junk, let the nearest Time Agent track it back to Earth, convince him it's valuable, name a price. When he's put fifty percent up front, oops! A German bomb falls on it, destroys it forever. He nevers gets to see what he's paid for, never knows he's been had. I buy him a drink with his own money, and we discuss dumb luck. The perfect self-cleaning con."

"Yeah, perfect," the Doctor said sarcastically.

"The London Blitz is great for self-cleaners," Jack advised. "Pompeii's nice if you want to make a vacation out of it though, but you've got to set your alarm for volcano day." He winced at the Doctor's glare. "Getting a hint of disapproval."

The Doctor gestured to the patients. "Take a look around the room. This is what your harmless piece of space junk did."

"It was a burnt out medical transport," Jack protested. "It was empty!"

"Girls, come on," the Doctor said, ignoring him.

"Ooh, are we getting out of creepy hospital land?" Alex asked hopefully.

"We're going upstairs," he told her.

"Oh!" she groaned.

Jack smiled. "I even programmed the flight computer so it wouldn't land on anything living. I harmed no one. I don't know what's happening here, but believe me, I had nothing to do with it."

The Doctor scoffed. "I'll tell you what's happening. You forgot to set your alarm clock. It's volcano day."

A loud wailing siren sound, interrupting them. Rose jumped. "What's that?"

"The all clear," Jack answered.

"I wish," the Doctor muttered.

***

How they had managed to lose the Doctor when they were literally following him, Alex didn't know, but it had happened.

"Mr Spock?" Jack called.

"Doctor?" Rose tried.

Suddenly, the Time Lord popped his head over the bannister in the stairwell. "Have you got a blaster?"

"Sure," Jack replied. They headed up the stairs, meeting the Doctor outside a steel door.

"The night your space junk landed, someone was hurt," he explained. "This was where they were taken."

"What happened?" Alex asked.

He shrugged. "Let's find out. Get it open."

Rose frowned as Jack got to work. "What's wrong with your sonic screwdriver?"

"Nothing," the Doctor replied.

"Ooh, sonic blaster!" Alex exclaimed, eyes widening as Jack blasted a small square hole in the door, taking out the lock. "Fifty-first century, right?"

"Weapon Factories of Villengard," the Doctor added.

Jack blinked. "You've been to the factories?"

The Doctor shrugged. "Once."

"Well, they're gone now," Jack told him. "Destroyed. The main reactor went critical. Vaporised the lot."

"Like I said," the Doctor grinned. "Once. There's a banana grove there now. I like bananas. Bananas are good." He went inside, Rose following.

"Nice blast pattern," Alex said, eyeing the hole in the door.

Jack raised his eyebrows, surprised. "Digital."

"Squareness gun?"

"Yeah."

She grinned. "I like it." They followed the others in, their smiles dropping when they saw the destruction inside. One half of the room was some sort of office, while the other was more of a child's room. There were crayon drawings on the wall, and broken glass on the floor.

"What do you think?" the Doctor asked, glancing across at Jack.

"Something got out of here," Jack said, eyeing the shattered observation window between halves of the room.

"Yeah. And?"

"Something powerful. Angry."

"Powerful and angry," the Doctor agreed.

"What do you think?" the Doctor prompted, his voice grim.

"I guess this explains 'Mummy'," Alex frowned, touching one of the drawings.

"How could a child do this?" Rose asked, shaking her head at the mess.

Behind them, the Doctor pressed play on a tape machine. The voice of Doctor Constantine projected into the room, followed by that of the child. "Do you know where you are?"

"Are you my mummy?"

"Are you aware of what's around you? Can you... see?"

"Are you my mummy?"

"What do you want? Do you know—?"

"I want my mummy. Are you my mummy? I want my mummy! Are you my mummy? Are you my mummy? Mummy? Mummy?"

Alex swallowed, getting to her feet. "Doctor, I've heard that voice before."

He met her eyes. "Me too."

"Mummy?"

"Always 'are you my mummy?'," she noted. "Like he doesn't know."

"Mummy?"

"Why doesn't he know?"

"Are you there, mummy?"

The Doctor went still, his brow furrowing. Rose raised an eyebrow. "Doctor?"

"Can you sense it?" he asked.

Jack blinked. "Sense what?"

He stretched a hand out. "Coming out of the walls. Can you feel it?" He realised they had no idea what he was talking about, and huffed a laugh. "Funny little human brains. How do you get around in those things?"

Alex rolled her eyes. "When he's stressed, he likes to insult species."

"Alex, I'm thinking."

"He cuts himself shaving, does half an hour on life forms he's cleverer then," she teased.

"There are these children living rough around the bombsites," he interrupted. "They come out during air-raids looking for food."

"Mummy, please?"

"Suppose they were there when this thing, whatever it was, landed," he suggested.

"It was a med-ship," Jack reminded him. "It was harmless."

"Yes, you keep saying harmless," the Doctor said. "What if one of them was affected, altered?"

Rose narrowed her eyes. "Altered how?"

"I'm here!"

"It's afraid," the Doctor realised. "Terribly afraid and powerful. It doesn't know it yet, but it will do. It's got the power of a god, and I just sent it to its room."

"Doctor," Rose said, hearing a ticking sound. "What's that noise?"

"End of the tape," he said. "It ran out about thirty seconds ago."

"I'm here, now! Can't you see me?"

"Oh God," Alex breathed, her eyes widening in realisation. "You sent it to its room."

The Doctor nodded. "This is its room." They turned to see the child staring at them, its head tilted innocently.

"Are you my mummy? Mummy?"

"Doctor?" Rose said, backing away.

"Alright," Jack said, taking charge. He reached for his sonic blaster. "On my signal, make for the door."

"Mummy?"

"Now!" He aimed at the child with... a banana?

The Doctor grinned, using Jack's blaster to make an escape route in the wall. "Go now! Don't drop the banana!"

"Why not!" Jack demanded, taking it with him anyway as they scrambled through.

"Good source of potassium!"

Jack rolled his eyes. "Give me that." He used the blaster to repair the hole seamlessly.

"Oh, digital rewind," Alex said appreciatively.

"Nice switch," Jack said, handing the banana back.

"It's from the groves of Villengard," the Doctor said, shrugging. "I thought it was appropriate."

"There's really a banana grove in the heart of Villengard, and you did that?" Jack looked surprised.

The Doctor smiled. "Bananas are good."

The wall cracked with the force of the child's blow. "Doctor!" Rose exclaimed.

"Come on!" They tried to run down the corridor, but the patients blocked them. Soon, they were cornered. "It's keeping us here till it can get at us."

"It's controlling them?" Jack asked, taking aim with his blaster.

"It is them," the Doctor corrected. "It's every living thing in this hospital except us."

"Okay," Alex said, biting her lip. "Well, I'm armed with my fists and a surprising amount of pent-up aggression. Jack?"

"This can function as a sonic blaster, a sonic cannon, and as a triple-enfolded sonic disruptor," he reported. "Doc, what you got?"

"I've got a sonic... er... Oh, never mind," the Doctor replied.

"What?"

"It's sonic, okay? Let's leave it at that."

"Disruptor? Cannon? What?" Jack asked.

"It's sonic," the Doctor assured him. "Totally sonic! I am soniced up."

"A sonic what?!"

"Screwdriver!"

The child broke through the wall.

Rose made a quick decision. "Going down!" She grabbed Jack's blaster, disintegrating the ground beneath their feet. They fell through to the dark ward below. Jack was on his feet in seconds, repairing the hole.

"Ow," Alex complained.

"Guys, are you okay?" Rose called, getting to her feet.

"Could've used a warning," the Doctor said pointedly.

Rose rolled her eyes. "Oh, the gratitude!"

"Need a hand, old man?" Alex teased, holding her hand out to the Doctor.

"Oi!" he protested, accepting it anyway. "I'm not old."

"You're nine centuries older that me," she reminded him, smirking, "which makes you old."

"Who has a sonic screwdriver?" Jack scoffed, joining them in the centre of the ward.

"I do," the Doctor exclaimed, pouting.

"Lights," Rose mumbled, searching the walls for a switch.

"Who looks at a screwdriver and thinks, ooh, this could be a little more sonic?" Jack snorted.

"There's got to be a light switch..."

"What, you've never been bored?" the Doctor countered. "Never had a long night? Never had a lot of cabinets to put up?" The lights came on, and all of the patients sat up.

"Mummy... mummy..."

"Door," Alex ordered, her voice tense.

Jack tried to use his blaster, but it had powered down. "Damn it! It's the special features," he complained. "They really drain the battery."

"The battery?" Rose echoed, unimpressed, as the Doctor soniced the lock. "That's so lame." They hurried into the room, locking the door behind them.

"I was going to send for another one, but someone's got to blow up the factory," Jack explained.

Rose rolled her eyes. "Oh, I know. First day we met him, he blew my job up. That's practically how he communicates."

"Okay, that door should hold it for a bit," the Doctor said, having locked it.

"The door?" Jack's brow furrowed incredulously. "The wall didn't stop it!"

"Well, it's got to find us first," the Doctor pointed out, shrugging. "Come on, we're not done yet. Assets, assets!"

"Well, he's got a banana, and in a pinch you could put up some shelves," Alex replied.

"Window?" he asked, seeing her climb onto a table to peer out of it.

"Barred, sheer drop outside," she answered. "Seven stories."

"And no other exits," Rose sighed.

Jack raised his eyebrows. "Well, the assets conversation went in a flash, didn't it?"

The Doctor narrowed his eyes, helping Alex down from the table. "So where'd you pick this one up, then?"

"Doctor..." she whined.

"She was hanging from a barrage balloon, I had an invisible spaceship," Jack told him, smiling. "I never stood a chance."

"Okay," the Doctor said simply, turning away to eye the barred window. "One, we've got to get out of here. Two, we can't get out of here. Have I missed anything?"

"Er, yeah," Rose told him. "Jack just disappeared."

"Oh," Alex said, looking disappointed.

Rose smirked at the Doctor's frown. "Okay, so he's vanished into thin air," she mused, deciding to help her sister along a little. "Why is it always the great looking ones who do that?"

The Doctor raised his eyebrows. "I'm making an effort not to be insulted here."

"I mean... men."

"Okay, thanks, that really helped."

Before they could say anything else, the radio on the desk crackled into life, a familiar American voice coming out of it. "Lexi? Rose? Doctor? Can you hear me? I'm back on my ship. Used the emergency teleport. Sorry I couldn't take you; it's security-keyed to my molecular structure. I'm working on it. Hang in there."

"How are you speaking to us?" Rose asked.

"Om-Com," Jack replied. "I can call anything with a speaker grill."

"Now, there's a coincidence," the Doctor frowned.

"What is?"

"The child can Om-Com too."

Alex blinked. "He can?"

The Doctor nodded. "Anything with a speaker grill. Even the TARDIS phone."

"What, the child can phone us?"

"And I can hear you," it called. "Coming to find you. Coming to find you..."

Alex shivered, even as Jack's voice replaced it. "Guys, can you hear that?"

"Loud and clear," Rose told him.

"I'll try to block out the signal," Jack said. "Least I can do. Remember this one, Lexi?" Through the radio, Moonlight Serenade began to play.

The Doctor raised his eyebrows, and Alex blushed. "Our song."

***

A little while later, Rose was scrolling through her phone, bored. She and Alex had commandeered wheelchairs, and on the other side of the room, Alex sat with the Doctor while he soniced the wall.

"What are you doing?" she asked, yawning.

"Trying to set up a resonation pattern in the concrete, loosen the bars," he replied quietly. Though he'd never say it, he quite enjoyed the little moments of tranquility they shared.

She sighed. "You don't think he's coming back, do you?"

"Wouldn't bet my life," he admitted.

"Why don't you trust him?"

"Why do you?"

"He saved my life," Alex pointed out. "Bloke-wise, that's up there with a nice bum and, to be fair, he's got that too." She smiled at the Doctor's raised eyebrows. "I trust him 'cause he's like you, except with dating and dancing." She narrowed her eyes when he stopped the sonic. "What?"

"You just assume that I'm..." he trailed off, shaking his head.

"What?" she asked curiously, her smile audible.

"You just assume that I don't dance."

She snorted. "What, you're telling me you do dance?"

"Nine hundred years old, me, I've been around a bit," he pointed out. "I think you can assume at some point I've danced."

"You?" she snickered.

He turned to look at her. "Problem?"

"Doesn't the universe implode or something if you dance?" she joked.

"Oi!" he protested. "I've got the moves, but I wouldn't want to boast."

Alex eyed him for a moment, then got to her feet, turning the music up. "Come on, then," she said, holding her hands out towards him. "You've got the moves? Show me your moves."

He sighed. "Alex, I'm trying to resonate concrete."

"Jack'll be back," she assured him. "He'll get us out. So go on. The world doesn't end because the Doctor dances."

After a moment, he joined her, taking her hands in his. He glanced at them. "Barrage balloon?"

She blinked. "What?"

"You were hanging from a barrage balloon?"

"Oh yeah." She made a face. "About two minutes after you two left me. Thousands of feet above London, middle of a German air raid, Union flag all over my chest. Yeah, that was fun."

The Doctor smiled. "I've travelled with a lot of people, but you're setting new records for jeopardy-friendly."

"Mmm. Is this you dancing?" she teased. "Because I've got notes."

"Hanging from a rope thousands of feet above London," he repeated. "Not a cut, not a bruise."

"Oh, I know. Captain Jack fixed me up."

He blinked, distracted. "Oh, we're calling him Captain Jack now, are we?"

"Well..." She tilted her head, pretending to think about it. "His name's Jack and he's a Captain, so...?"

"He's not really a Captain," the Doctor told her, his voice soft.

"Do you know what I think?" she said, putting her hands together at the back of his neck. "I think you're experiencing captain envy. You'll find your feet at the end of your legs, you may care to move them."

He smiled, resting his hands on her waist. "If ever he was a captain, he's been defrocked."

"Yeah?" She grinned. "Shame I missed that."

"Actually, I quit," Jack corrected. "Nobody takes my frock." The three of them looked up to find they were now standing in Jack's ship. "Most people notice when they've been teleported." He pointed at the Doctor and Alex, who were still holding each other. "You guys are so sweet. Sorry about the delay. I had to take the nav-com offline to override the teleport security."

The Doctor raised an eyebrow. "You can spend ten minutes overriding your own protocols? Maybe you should remember whose ship it is."

"Oh, I do," Jack smiled dazzlingly. "She was gorgeous. Like I told her, be back in five minutes."

Rose rolled her eyes at him. "So is this a Chula ship?"

"Yeah, just like that medical transporter," Jack confirmed. "Only this one is dangerous."

The Doctor snapped his fingers, and a golden glow enveloped his hand. "Oh!" Alex exclaimed, smiling fondly at the tiny butterfly things. "They're what fixed my hands up. Jack called them... oh, what was it?"

"Nanobots?" the Doctor suggested. "Nanogenes?"

"Nanogenes, yeah, that's it."

"Sub-atomic robots," he explained. "There's millions of them in here, see? Burned my hand on the console when we landed. All better now. They activate when the bulkhead's sealed. Check you out for damage, fix any physical flaws." He snapped his fingers again, and they disappeared. "Take us to the crash site," he ordered Jack. "I need to see your space junk."

"As soon as I get the nav-com back online," Jack agreed. "Make yourselves comfortable. Carry on with whatever it was you were doing." He smirked.

The Doctor blinked. "We were talking about dancing."

Rose snickered. "It didn't look like talking."

"It didn't feel like dancing," Alex teased.

***

A little while later, while the Doctor and Alex tried dancing again, Jack and Rose were sitting in the pilots' seats, chatting.

"So, you used to be a Time Agent, but now you're trying to con them?" Rose asked.

Jack winced. "If it makes me sound any better, it's not for the money."

She frowned. "What's it for then?"

"Woke up one day when I was still working for them, found they'd stolen two years of my memories," he confessed. "I'd like them back."

Rose stared. "They stole your memories? That's horrible."

"Two years of my life, no idea what I did." Jack nodded, glancing over at the Doctor and Alex. "Your friend over there doesn't trust me, and for all I know, he's right not to." Something on the console bleeped, and he took the opportunity to change the subject. "Okay, we're good to go. Crash site?"

***

The four of them stood at the top of the hill, Jack pointing down at a tarpaulin-covered lump with soldiers milling around it. "There it is. Hey, they've got Algy on duty. It must be important."

The Doctor bit his lip. "We've got to get past him."

Rose raised her eyebrows. "Are the words 'distract the guard' heading in my general direction?"

"No," Jack told her flatly.

She blinked. "What? I can handle it!"

"It's not that," Jack assured her. "I've got to know Algy quite well since I've been in town. Trust me, you're not his type. I'll distract him. Don't wait up." He headed off down the hill.

"Relax," Alex told her sister, seeing her surprised expression. "He's just a bit more flexible when it comes to dancing."

"How flexible?" Rose asked.

"Well, by his time, you lot have spread out across half the galaxy," the Doctor told her.

She shook her head. "Meaning?"

He grinned. "So many species, so little time."

"So that's what we do when we get out there, then?" Alex asked. "We seek new life and...?"

"Dance."

She raised an eyebrow at him. "Well, you're going to have to dance better then."

Rose snorted. She glanced down to see how Jack was doing, and frowned. "What's he doing?"

The Doctor followed her gaze, seeing Algy on his knees, his face transforming into a gas mask. "Stay back!" They ran down the hill.

Jack held his hands out to the advancing soldiers. "You men, stay away!"

"The effect's become airborne," the Doctor realised. "It's accelerating."

"What's keeping us safe?" Rose asked.

The Doctor winced. "Nothing."

The air raid siren started up, making Jack look up. "Ah, here they come again."

"Jack, didn't you say a bomb was going to land here?" Alex said, biting her lip.

"Never mind that," the Doctor said quickly. "If the contaminant is airborne now, there's hours left."

"For what?" she asked.

He met her eyes. "Till nothing. Forever. For the entire human race." He blinked, distracted. "Can anyone else hear singing?" He followed the sound to a nearby shed, returning with a frightened Nancy.

***

"You see?" Jack said later, as they uncovered the Chula ship. "Just an ambulance."

Nancy blinked. "That's an ambulance?"

"It's hard to explain," Rose told her. "It's from another world." Nancy raised her eyebrows, but didn't comment.

"They've been trying to get in," Jack frowned.

The Doctor rolled his eyes. "Of course they have. They think they've got their hands on Hitler's latest secret weapon."

"What are you doing?" Alex asked as Jack keyed a code into the access panel.

"The sooner you lot see this thing is empty, the sooner you'll know I had nothing to do with it," he said. Right on cue, the keypad sparked and an alarm sounded. Jack frowned. "Didn't happen last time."

"It hadn't crashed last time," the Doctor pointed out. "There'll be emergency protocols."

Rose stared as the patients began to batter at the gates to the hospital. "Doctor, what is that? Doctor!"

He looked up, his eyes widening. "Captain, secure those gates!"

"Why?" Jack asked, then he saw the patients.

"Just do it." The Doctor turned to Nancy. "Nancy, how'd you get in here?"

"I cut the wire," she admitted.

"Show Rose," he ordered, throwing the blonde his screwdriver. "Setting two thousand four hundred and twenty eight D."

Rose blinked. "What?"

"Reattaches barbed wire," he explained. "Go!"

They went, and he and Alex turned back to the ship. They were just prising the door open when Jack returned. "It's empty. Look at it."

"What do you expect in a Chula medical transporter? Bandages? Cough drops?" He turned to the blonde. "Alex?"

"What? I don't know." She shook her head distractedly, glancing up as a bomb whistled past.

"Yes, you do," he said, snapping his fingers.

Her eyes widened. "Nanogenes!"

He nodded. "It wasn't empty, Captain. There were enough Nanogenes in there to rebuild a species."

Jack blanched. "Oh God."

"Getting it now, are we?" The Doctor raised his eyebrows as Rose and Nancy returned. "When the ship crashes, the nanogenes escape. Billions upon billions of them, ready to fix all the cuts and bruises in the whole world. But what they find first is a dead child, probably killed earlier that night, and wearing a gas mask."

"And they brought him back to life?" Rose realised. "They can do that?"

He shrugged. "What's life? Life's easy. A quirk of matter. Nature's way of keeping meat fresh. Nothing to a nanogene. One problem, though. These nanogenes, they're not like the ones on your ship. This lot have never seen a human being before. Don't know what a human being's supposed to look like. All they've got to go on is one little body, and there's not a lot left. But they carry right on. They do what they're programmed to do.

"They patch it up, can't tell what's gas mask and what's skull, but they do their best. Then off they fly, off they go, work to be done. Because you see, now they think they know what people should look like, and it's time to fix all the rest. And they won't ever stop. They won't ever, ever stop. The entire human race is going to be torn down and rebuilt in the form of one terrified child looking for its mother, and nothing in the world can stop it!"

Jack stared, horrified. "I didn't know."

The patients advanced, battering the barbed wire surrounding the bombsite. Nancy's eyes widened. "Rose!" They all backed towards the ambulance.

Alex swallowed. "It's bringing them here, isn't it?"

The Doctor nodded, sonicing the base of the spacecraft. "The ship thinks it's under attack. It's calling up the troops. Standard protocol."

Rose frowned. "But the gas mask people aren't troops."

"They are now," he told her. "This is a battlefield ambulance. The nanogenes don't just fix you up, they get you ready for the front line. Equip you, programme you."

"That's why the child's so strong," Alex realised. "Why it could do that phoning thing."

"It's a fully equipped Chula warrior, yes," he agreed. "All that weapons tech in the hands of a hysterical four year old looking for his mummy. And now there's an army of them." The patients stopped, staring at the five of them.

"Why don't they attack?" Jack asked, eyes wide.

"Good little soldiers," the Doctor explained. "Waiting for their commander."

"The child?" Alex guessed.

"Jamie," Nancy corrected.

"What?"

"Not the child," she insisted. "Jamie."

"So," Rose said, glancing up at the fighter planes above. "How long until the bomb falls?"

"Any second," Jack replied.

The Doctor scoffed. "What's the matter, Captain? A bit close to the volcano for you?"

"He's just a little boy," Nancy sighed.

"I know," Alex told her, squeezing her shoulder.

"He's just a little boy who wants his mummy."

"I know," the Doctor repeated. "There isn't a little boy born who wouldn't tear the world apart to save his mummy. And this little boy can."

"What are we going to do?" Alex asked him, trying not to let her voice tremble.

He swallowed hard, meeting her eyes. "I don't know."

"It's my fault," Nancy wept.

"No," the Doctor assured her.

"It is," she insisted. "It's all my fault."

"How can it be your—?"

"Mummy..."

The Doctor's eyes widened. "Nancy, what age are you? Twenty? Twenty-one? Older than you look, yes?"

"Doctor, that bomb," Jack warned nervously. "We've got seconds."

"You can teleport us out," Rose told him.

He shook his head. "Not you guys. The nav-com's back online. Going to take too long to override the protocols."

"So it's volcano day," the Doctor told him. "Do what you've got to do."

Jack met Rose's eyes apologetically, and beamed away.

"How old were you five years ago, Nancy?" the Doctor continued. "Fifteen? Sixteen? Old enough to give birth, anyway. He's not your brother, is he?" Nancy shook her head tearfully. "A teenage single mother in 1941, so you hid. You lied. You even lied to him."

The gate to the bombsite creaked open, and Jamie stood, staring. "Are you my mummy?"

"He's going to keep asking, Nancy," the Doctor told her. "He's never going to stop. Tell him. The future of the human race is in your hands. Trust me and tell him."

"Are you my mummy?"

"Yes," Nancy said, walking towards her son. "Yes, I am your mummy."

"Mummy?"

"I'm here," she sighed.

"Are you my mummy?"

"I'm here."

"Are you my mummy?"

"Yes."

"Are you my mummy?"

"He doesn't understand," Alex worried. "There's not enough of him left."

"I am your mummy," Nancy told him firmly. "I will always be your mummy. I'm so sorry. I am so, so sorry." She hugged him to her, and a cloud of nanogenes surrounded them.

Rose stared. "What's happening? Doctor, it's changing her, we should—!"

"Come on, please," he begged. "Come on, you clever little nanogenes. Figure it out! The mother, she's the mother. It's got to be enough information. Figure it out!"

"What's happening?" Alex asked, realising the nanogenes weren't changing Nancy.

"See? Recognising the DNA." The Doctor bit his lip as mother and son fell to the ground, the golden glow dissipating. "Oh, come on. Give me a day like this. Give me this one." He reached out and removed Jamie's gas mask, revealing a smiling little boy. "Haha! Welcome back!" he cheered. "Twenty years till pop music; you're going to love it!"

Nancy frowned, sitting up. "What happened?"

"The nanogenes recognised the superior information, the parent DNA," the Doctor explained. "They didn't change you because you changed them. Haha! Mother knows best!"

"Oh, Jamie." She hugged her son, sighing in relief.

"Doctor, that bomb," Rose warned, glancing at the sky.

He grinned. "Taken care of it."

Alex blinked. "What? How?"

"Psychology."

The bomb hurtled towards them, but stopped in mid air, caught in Jack's tractor beam. The man himself was straddling the bomb, smiling down at them. "Doctor!"

"Good lad!"

"The bomb's already commenced detonation," Jack explained. "I've put it in stasis, but it won't last long."

The Doctor winced. "Change of plan. Don't need the bomb. Can you get rid of it, safely as you can?"

Jack nodded. "Girls?"

"Yeah?" they said, peering up at him.

"Goodbye!" Jack and the bomb vanished, reappearing a second later. "By the way..." He winked at Alex. "Love the T-shirt!"

She beamed, and he disappeared. Next to her, the Doctor snapped his fingers, summoning the nanogenes. "What are you doing?" Rose asked, grabbing her sister's attention.

"Software patch," the Doctor said. "Going to email the upgrade. You want moves, Alex? I'll give you moves." He thrust the nanogenes into the crowd of waiting patients, converting them all back to their natural states. As they stumbled to their feet, the Doctor swept the two sisters into a hug. "Everybody lives, girls. Just this once, everybody lives." Then he was off to chat to Dr Constantine.

Rose turned to her sister, grinning. "So, the Doctor dances, eh?"

Alex blushed. "Shut up." But she was grinning too, a wide, happy smile she hadn't worn in far too long.

The Doctor rejoined them and started to fiddle with the ambulance controls. "Setting this to self-destruct," he explained. "Soon as everybody's clear. History says there was an explosion here. Who am I to argue with history?"

Alex snorted. "Usually, first in line!"

***

As they returned to the TARDIS, he was finishing his explanation, with a smile like the Cheshire Cat. "The nanogenes will clean up the mess and switch themselves off, because I just told them to. Nancy and Jamie will go to Doctor Constantine for help, ditto. All in all, all things considered, fantastic!"

Rose chuckled. "Look at you, beaming away like you're Father Christmas."

"Who says I'm not?" he countered, pointing at her. "Red bicycle when you were twelve."

She blinked. "What?"

"And everybody lives, girls," he continued. "Everybody lives! I need more days like this."

"Doctor," Alex said patiently, unable to hide a fond smile.

"Go on," he said, "ask me anything. I'm on fire!"

"What about Jack?" she asked. "We're not leaving him with that bomb, are we?" The Doctor just grinned.

***

Captain Jack Harkness sat in the pilot's seat in his spaceship, drinking a final martini and reminiscing about his adventures. Slowly, as the memories drifted past, something else drifted in: music. He turned to see the open doors of the TARDIS, Moonlight Serenade playing. Inside, the Doctor and Alex were dancing again, Rose watching with a smile.

"Well, hurry up, then!" she called, glancing at him over her shoulder. He did as he was told, abandoning his drink.

"Okay, and right, and turn," Alex was saying as she and the Doctor attempted to perfect a sequence, unsuccessfully. She laughed. "Okay, okay, try and spin me again, but this time don't get my arm up my back. No extra points for a half-nelson."

"I'm sure I used to know this stuff," he pouted, letting her go. He glanced over at Jack. "Close the door, will you. Your ship's about to blow up. There's going to be a draught." The captain did so, and the Doctor threw the dematerialisation lever.

"Welcome to the TARDIS," Rose smiled.

"Much bigger on the inside," Jack noted, looking around in awe.

"You'd better be," the Doctor muttered, not looking up.

"I think what the Doctor is trying to say is, you may cut in," Alex said, holding a hand out to Jack.

The song changed, and the Doctor straightened, his eyes widening. "Alex! I've just remembered!"

"What?" She couldn't help but smile at his excited grin.

"I can dance! I can dance!"

She rolled her eyes. "Actually, you know, I thought Jack might like this dance."

"I'm sure he would, Alex," the Doctor smiled. "I'm absolutely certain, but who with?"

She laughed, giving in, and took his hand. He spun her into his arms and they started to dance, properly this time. Jack took Rose's hand, and the two couples danced around the central console, each of them beaming. And when the music ended, and the Doctor dipped her, Alex could have sworn she was the happiest girl alive.

~~~