A dull sound, which became progressively more insistent and shrill, intruded on her consciousness. It was some sort of an alarm. She opened her eyes, blinking against the dazzling light. "Doctor?" she called.

"I'm here, child."

A face came into view. It wasn't the man with the curls and frills. This man was much older. He had shoulder-length white hair and wore an odd sort of black hat. Rose squeezed her eyes shut and opened them again. He was in Edwardian dress: a black frock coat and check trousers.

"The Dalek?" she whispered hoarsely.

"No Daleks here."

Rose shook her head, and sat up, painfully. She looked around. It became abundantly clear to her why the Proprietor kept the lights so dim; under the harsh emergency lights, it was obvious that the black fabric covering the walls was worn and dusty; and the black carpet faded and stained. "What happened?"

"That's what I was going to ask you," said the Doctor, eyeing her suspiciously.

She fumbled in her pocket for the note; it wasn't there. She thought back; and realised the last Doctor had dropped it. She rose to her feet, wobbling slightly. She scanned the corridor--there it was, at the far end. "Over there," she gestured. "Your...er...counterparts have been writing in it. You'll be able to work it out."

The Doctor gazed at her skeptically, then moved to retrieve the note. He stared at it for a moment, then crumpled it up. "A funny sort of game you're playing, hmm?" he snarled. "This is blank."

"Blank?" said Rose. "Give it here." Scowling, he tossed it to her. She caught it, and opened it up. She glanced at it, then flipped it around, holding it up for him to see. "It's not blank at all, look."

He strode towards her quickly, and snatched the paper from her hands. "How very odd," he said, reading it. "How very odd indeed. Rogue universe?"

"It's mine, my universe" said Rose. "Where I'm from. The Time Lords were killed, there's only one left--"

"Bah," said the Doctor. "I don't believe that's it. The universe existed very well before the Time Lords, I doubt it will miss them when they're gone. What did the Time Lords ever do for anybody?"

Rose was too astonished to reply.

"But I do think," he said, glancing from the note to Rose and back again, "it is quite possible you are the problem. Give me your hand."

"How can it be me?" she protested, as he grabbed one of her fingers. The Doctor took the probe off the Proprietor's desk and pressed it against her skin.

"Aha, just as I expected. You've got two matter signatures, verifying that you've spent time on two separate parallel universes. Mostly Zed Zed Alpha, where you're from originally, I take it; and also Zed Zed Theta. Tell me," he said, releasing her hand. "What's unusual about Zed Zed Theta?"

" Zed Zed Theta," said Rose. "Where—there still are Time Lords?"

"Yes, you silly girl. The other universe you have visited. What is unique, what is unusual about it?"

"Erm..." Rose tried to think. "Cybermen?"

"No, every humanoid race manages to dream up Cybermen at some point, as far as I'm aware. Think, child!"

She massaged her temples. There was something--what was it?

"Daleks!"

"Fool," he snapped. "Daleks are everywhere--"

"No!" she cried. "There aren't any Daleks in... Zed Zed Theta. They're Kaleds."

"Kaleds," said the Doctor, leaning forward. "Tell me everything you know about Kaleds."

"Well, they work at the restaurant--"

"Do they, now? What else?"

"And...and...they're very peaceful...erm..." What had the Doctor told her at dinner? What had he said? She swallowed. "They are...engineers...good engineers...they preserved dying races when the stars went out."

"How the devil did they do that?" cried the Doctor.

"I don't know," said Rose, now feeling very agitated. "I don't know! No--wait. Something about dark energy. Yes, that's it, they harnessed dark energy."

His eyes widened. He stared at her for a moment without speaking. Then, softly, he said, "Child, do you know what happens if you 'harness' dark energy?"

She shook her head no.

"You get more dark energy. The more you use, the more you create. Ingenious, isn't it?"

She found his tone quite disturbing. She nodded slightly.

"NO!" He gripped her shoulders hard and shook her. "Because the more dark energy there is, the faster and faster and faster the galaxies, stars, and planets fly apart from one another, and then...do you know what happens?"

She stared at him transfixed, unable to move or speak. He slowly released his hands from her shoulders and held up the note. He tore it in half. "The Big Rip."

"W-what's that?" she stammered.

"I don't have time to explain," he said, suddenly, flinging the torn pieces of paper at her. "I've got to get out of here. Because of your dual matter signature, you are the prime source of instability, you are breaking down the barriers, and if you stay, you will destroy this place."

"How do I leave? Y-you've got to help me!"

"Oh, it's very easy. Fling yourself out the nearest air lock. Your life is so short, human, what does it matter if it ends now or a few years hence?" And with that parting epithet, he hurried down the corridor and out of sight.