The Doctor yanked a lever on the TARDIS console. The entire chamber lurched to one side, nearly throwing both the Time Lord and Rose off their feet.

"'Ere, watch it!" Rose said. She pouted her full lips. "I'm still not comfortable traveling with you. I certainly wouldn't be comfortable if you dashed me to the floor!"

"Sorry," said the Doctor. He flashed his companion a winning smile – although, admittedly, not as winning a smile as his predecessor was capable of. Rose couldn't conceal her disappointment at his recent regeneration. In her mind, he remained a brooding character whose dark moods were occasionally (and unpredictably) shattered with a beautiful, ear-to-ear grin. This new Doctor, though superficially cheerful, was difficult to read, and Rose's working-class mind was stymied by his complexities.

Rose tossed her blonde hair. "Where are we going, anyway?" she drawled.

He turned to her. "Oh, you'll like this," he said. "It's a pocket dimension. Been there a couple of times, though not recently. Branched off of what you'd call Earth Prime about ten thousand years ago. Populated by humans – wellll, near-humans, not quite the genuine article, but close enough for government work – and interdimensional ethnological resonance has caused the inhabitants to mimic various Asian cultures. Is it just me or is it getting cold in here?"

Rose, who was getting used to this Doctor's sudden topic shifts, glanced toward the TARDIS door. Its tiny windows were solid white.

"'Ere," she said. "Cor blimey, but it is cold."

A gentle shudder and the throb of chronobrakes suggested that the time machine had touched down. The Doctor strode to the door on his lanky, slender legs and shoved it open. Snow blew into the TARDIS, carried by a wave of frigid wind.

The Doctor slipped on his spectacles. "Ooh, that's beautiful," he said. Rose walked up behind him and looked out the door.

As she peered through the blizzard endless fields of glittering ice, broken only by patches of clear blue water, met her vision. Here and there mountainous icebergs thrust through what Rose would tentatively call "the ground," lending the planet a hostile, uninhabitable air. Not for the first time, she faintly wished she had remained home with Mickey instead of following this mysterious new Doctor.

"Is that it?" she said dubiously. "Seems a bit of rubbish to me."

The Doctor looked at her, one eyebrow raised. "Really? Rubbish?" He cocked his head to one side. "Wellll, I'll be the first to admit it's not exactly a holiday in Sorrento, but once you get used to the temperature you'll find that it's really quite..."

The blizzard abated momentarily, revealing a fur-clad hunting party. They scowled at the travelers and raised their spears menacingly.

"...pleasant," said the Doctor. He swallowed. "Er. Is this a bad time to visit?"

What Rose really objected to, she thought, was the blindfold. It wasn't even as though there was much to see in this Arctic wasteland, but nevertheless it grated at her. Apart from that, their captors had been reasonably friendly, going so far as to provide her with a smelly but warm fur coat during their long canoe trip back to the village.

After further thought, she reconsidered. What she really objected to was the fact that she and the Doctor had been loaded into separate canoes. She hadn't heard the Time Lord's voice in what must have been two hours, and although she had every confidence the Doctor would rescue her, the waiting was murder on her nerves.

At long last her captors lifted her from the bottom of the boat, unbound her legs, and marched her out onto a snowy bank. Rough mittened hands shoved down on her head, preventing her from striking her skull on a low ceiling.

"Molto bene!" said a familiar voice. "Rose, I'd like you to meet an old friend of mine."

Unseen hands undid her blindfold. Rose's eyes adjusted to the dark and saw...

...the Doctor, sitting comfortably on a pile of furs in his ill-fitting pinstriped suit, next to the most beautiful woman Rose had ever seen. She was young, perhaps Rose's age, and though her skin was dark as milk chocolate her eyes were the piercing blue of the summer sky. Her near-black hair was tied up in an elaborate style and hung in dark loops across her face, which bore a serene but remarkably intelligent expression.

Looking around, Rose realized that she was inside an igloo. She was surprised by how warm it was, and shrugged off the fur coat. "Who's this?" she said jealously.

"This is Katara," said the Doctor. "She's Chieftess of the Southern Water Tribes. See, there's four nations: Earth, Wind, and Fire..."

"Air," Katara gently corrected him. Her voice was as melodic as the crashing of waves upon a shore.

"Air. Right. Sorry. Had a flashback to the Seventies again. Earth, Air, Fire, and Water. They've historically lived in peace, although a few years back they were having some trouble with the Fire Nation, is that right?"

Katara nodded gravely. "Some truly dark times have come and gone since you last visted us, Doctor," she said. "We could have used your counsel five years ago, Doctor. Gran-Gran spoke of you sometimes – she told stories of the Northern Water Tribe, whose legends recount a traveller who would occasionally appear in a blue box and offer cryptic advice."

"Cryptic?" said the Doctor, arching an eyebrow.

Katara laughed, a sound like the tinkling of icicles. "Don't be offended," she said. "Whether or not they were in a position to understand it, the Water Tribe has always valued your advice. But even without your help we managed to unseat the Fire Lord and restore a measure of harmony to this beleaguered world."

"Good on you!" said the Doctor. He moved as if to give Katara a friendly slap on the back, seemed to think better of it, and swung the arm around to adjust his tie instead. "Only..." he trailed off, then screwed up his face in concentration. He sniffed at the air once or twice, experimentally.

"Something's not right," he said. "The balance is... off."

Katara nodded. "The Air Nomads have been devastated. Their population has been reduced... to one, in fact. My betrothed is the only remaining member of their nation. And he's..." Katara's voice cracked with emotion, and she looked away to hide the tears.

" no lift in his glider?" finished the Doctor.

Katara glared at him, her ice-blue eyes flashing.

"Don't get me wrong," said the Doctor. "Last of his kind? I know how it works, believe me. And I think I may have just the solution. You see, where I come from, we're not born – our genetic material is, or was, woven from a fantastic device called the..."


Rose wheeled to look at another person entering the igloo. Though shorter than the Doctor, his bearing suggested a poise and agility on par with a Time Lord, and he was dressed in filmy red and gold fabrics rather than heavy furs. His face was young but careworn, and his shaved head bore a blue arrow-shaped tattoo.

"Oh," said Katara, blushing. "Doctor, this is my betrothed. Aang, I'd like you to meet the Doctor."

Aang bowed slightly. "Katara, I've just returned from the outpost. It's about the Fire Nation."

"'Ere, the Fire Nation?" asked Rose.

Aang's grey eyes focused on the Doctor's companion. "That's right," he said. "They're attacking."

The Doctor, Katara, Aang, and Rose looked out across the sea. A group of Water Tribe warriors milled around behind them, uncertainly fingering their swords and shouldering their spears. Off in the distance, near the horizon, a ship drew ever closer. Even those without the benefit of the Doctor's Gallifreyan eyes could see that the ship was from the Fire Nation – and, if there had been any doubt, the flakes of black ash drifting from the sky would have settled the argument.

"Is it Zuko?" asked Katara, but without much hope.

Aang shook his head. "He would have sent a message first. Besides, when I flew near the ship, they shot at me."

"'Ere, can't we take them out from a distance?" said Rose.

The Doctor's eyes widened. "Without hearing them out?" he said. "That just isn't cricket."

"I agree," said Aang. "Friend or foe, we need to see why they're here first."

Presently the terrible metal ship glided like a bear-shark up to the village and, with a resounding crash, collided with the ice sheet on which Katara's village lay. Thick clouds of acrid black smoke belched from its stacks, choking the sky, and before long a ramp extended from the front of the ship and clattered against the ice.

A female figure walked down the ramp, flanked on each side by a distinctly non-human shape.

"Azula," Katara breathed. Aang readied his staff.

"Daleks?" Rose gasped. The Doctor raised his Sonic Screwdriver.

Azula turned and regarded the two pepper-pot machines on either side of her. "Is that what they're called?" she said with a lopsided smirk. "All I cared about was that they weren't human. Humans are traitors, you know. Mai and Ty Lee? They betrayed me. Me!" she roared, and blue streams of lightning crackled around her like a terrifying halo. "These 'Daleks,' as you call them? They freed me from prison. They killed Zuko. They won't betray me. They're loyal. And loyalty is a quality that's so difficult to find these days."

"Don't be stupid, Azula," said the Doctor, wielding his Screwdriver as a knight would a sword. "Daleks are racial supremacists, bent on wiping out all non-Dalek life in the multiverse. They'll turn on you the first chance they get."

"COR-RECT!" announced one of the Daleks. It glided down the ramp and onto the ice. "HU-MAN AZULA WAS MERE-LY A MEANS TO AN END! THE DAH-LEK EM-PIRE WILL RISE AGAIN!"

The other Dalek rotated its roundel-studded torso and a green lance of energy streaked toward Azula. Before she had time to so much as shriek in surprise she was dead, a smouldering, broken shape against the ice.

"Rose! Look out!" shouted the Doctor, as a second beam arced through the bitterly cold air.

"'Ere..." said Rose, and exploded into a fountain of gore. Her blonde head, its eyes still frozen in an expression of surprise, landed in a snowbank and stared mutely at the Time Lord.

"Nooo!" the Doctor screamed. Drawing upon a sun's worth of fury, he waved his Sonic Screwdriver. Instantly the two Daleks were reduced to dust.

The Doctor collapsed to his knees. Katara and Aang rushed to his side. Meanwhile, the Water Tribe warriors climbed the ramp and began to methodically search the Fire Nation ship, hunting down any survivors.

"I... promised myself I'd never do that," the Doctor mumbled. "I promised I'd never... oh, Rose..." His hands gestured feebly at the crimson splash in the snow that had once been his companion.

"It's all right," said Aang. "As Avatar I've found I've had to do things to protect my loved ones that violate my ethical code as an Air Nomad."

"But I couldn't save her," the Doctor moaned.

Katara looked into the Doctor's red-rimmed eyes, seeing the layers of hurt and guilt buried there, seeing the literal eons of loneliness that burned within his unfathomably vast mind. She laid a warm hand on his shoulder. "You did all you could," she said.

The Doctor stood up, unsteadily, and brushed the snow from his slacks. A new determination had entered his eyes – a cold, steely resolve.

"I couldn't save Rose," he said. "But I can save this world. I will restore the Air Nomads." He extended a hand to Katara and Aang, who glanced at each other before turning back to the Doctor and nodding their assent.

"We need to find the Loom," he said.