Cara ran. And ran. And ran. On and on into the night, without stopping. They were after her again. The faceless attackers.

She woke up, gasping. Her eyes roamed the unfamiliar surroundings until she realized that she had no idea where she was, but that it was white and stretched on infinitely. Her head hurt.

The Doctor's face appeared over her, "You have no right to scare me like that. In the middle of a nice dance, too."

"What happened?" Cara glanced down at her hands, "why am I blotchy? And…on ice?"

"Well, I had to keep you from burning up from the inside out," the Doctor replied, "it seems you literally suffered from 'night fever'."

"Oops," Cara groaned.

"It's all right," the Doctor smiled, concern in his eyes, "Antarctica wasn't that far away."

Cara stood up and looked at where she had been lying. The ice was blackened and scorched-looking, "I burned ICE?"

The Doctor shrugged, but stared, too, "You heated up faster than it could melt."

"I didn't…" she looked down, "change did I?"

"Oh, no," the Doctor assured her, "just a fever, you slept it off."

"You make it sound like a hangover," Cara stepped into the TARDIS. She giggled, "I don't remember getting drunk." She stopped giggling when the Doctor came in, still looking concerned and deep in thought.

"What is it? I feel fine now," Cara smiled at him, "see, there was this Doctor there who helped me out…"

The Doctor looked straight into her eyes, "Where's the primary oscillator circuit in the TARDIS?"

"Uh," Cara blinked, "I don't know, why?"

"You should," the Doctor insisted, "we repaired it yesterday. In fact, you were the one who pointed out that there was a problem with it."

Cara looked silently back at him.

He put his hands on her shoulders firmly, "this is very important. Have you noticed anything odd lately? Hallucinations, recurring nightmares, flashbacks, deja-vu?" He searched her face.

"Nightmares," Cara whispered, "like bad memories that I never had."

The Doctor's face fell, "So it's begun." He looked away, "I was afraid of this."

"What?" Cara grabbed his arms, "what is happening to me?"

The Doctor looked at her with anguished eyes, "You're trying to hold back a lifetime of memories and they're starting to break through the barrier. But your mind would sooner tear itself apart than let these memories get loose. And that's what's happening. It's coming apart."

"So what happened at the roller rink," Cara began.

"Minor short-circuit," the Doctor shook his head, "just a small skirmish in the war going on inside you."

"There's nothing we can do," Cara realized, "either I lose all of my memories forever, or I lose my mind. Or…" She stopped.

"No."

"If I regenerated…"

"It might be the last time you ever did," the Doctor cried, "I can't let you take that chance. There's got to be another way!"

"There is," Cara said softly, "I could remember."

"And I would lose you forever," the Doctor's gaze was eternal, "we'd be on opposite sides. Enemies."

"Was that how it was in the war?" Cara demanded, "was I some sort of traitor?"

The Doctor shook his head, "you're right, there's nothing we can do."

"Doctor!" Cara growled through her teeth, "I…"

"What?" he exploded in frustration.

"I…" she repeated, "I…don't want to forget this." She took his hand.

The Doctor opened his mouth just as the TARDIS did a somersault. Cara and the Doctor grabbed for the nearest pillar and clung to it until the twirling sensation turned into a swaying motion. The Doctor ran to the console and held on while he checked readings, "What?"

"We were sitting on miles of permanent glacier," Cara slowly loosened her grip on the pillar, "why does it feel like we're in water?"

"It's gone," the Doctor explained disbelievingly, "the whole of Antarctica. Just…gone! Looks like all of the ice suddenly melted, and the land is underwater. Blimey, you're not that hot! What was it?"

"Not that hot?" Cara moved beside him. She frowned at the readings, "When are we?"

"Still 1987," the Doctor's brow furrowed, "just hopped across continents."

"Funny how I remember Antarctica being here 20 years from now," Cara mused, "of course, we've just established that my memory isn't 100% reliable…"

"Something's interfered with the time stream, and it wasn't us," the Doctor started operating the TARDIS, "which leaves one other possibility." He nodded at Cara, eyes twinkling. She nodded back.

The wooden blue box, floating at the bottom of the world, faded out of the ocean.