"You haven't just been turned into a wooden dolly."

The Doctor waved Amy's comment aside, fiddling with knobs and levers on the TARDIS console without any real plan in mind. "You turned back, didn't you? What was it like, being wood? I couldn't get a reading off of you … I really need a setting for that, honestly … nine hundred years and my sonic doesn't do wood."

"That's rubbish," Rory said matter-of-factly.

"Oi!"

Amy smiled, but it slipped from her face when the Doctor suddenly started pressing buttons and pulling levers and twisting knobs with more fervour than usual. There was a slightly alarmed expression on his face, which Amy found more than slightly alarming in itself.

"Doctor," she started, but he began mumbling to himself, darting from panel to panel, smacking screens, frowning, always frowning, and all the time muttering, "No, no, no, no."

"Doctor, what is it?" Amy asked, stepping back hurriedly as he whirled around the console.

He stopped moving abruptly, and looked up at them, something like fear flickering behind his eyes. "It's impossible," he said quietly.

There was an ear-splitting grinding noise, and a powerful wrench that sent them all off balance and falling to the floor. Prepared for a bumpy ride, Amy clutched at the railing, but nothing more happened. Slowly, the three of them straightened, and Rory put a hand on her face anxiously.

"Are you okay?"

"I'm fine," she said, staring about her with a small frown on her face.

"That's not right," the Doctor said, looking around, turning in a circle on the spot. "Something's gone funny with the TARDIS."

"Again?" Rory groaned, just as Amy said, "You picked up on that, then?"

The Doctor remained still for a split second before bounding down the walk and to the door. He threw it open and almost stepped out, but caught himself just in time. Amy and Rory came up behind him.

"Huh," Rory said.

They were hanging in space, turning slowly, blackness and tiny pinpricks of light in every direction.

The Doctor shut the door and turned back to face the console room.

Amy looked, too. It was the same, it was their TARDIS, but at the same time there was something … off. Like she was looking at it from the wrong angle, or everything was a shade too big or small. Like it had contorted so minimally that she wouldn't have noticed it if she hadn't been looking for something out of place.

"Where are you?" the Doctor said, quietly at first. And then, "Where are you?" He strode to the middle of the room and circled the console, staring up the staircases and into darkened doorways. "Go on, show yourself, show yourself, I know you're here!" He was shouting now, and Amy and Rory exchanged a confused look.

Laughter. The three of them turned as one to face the nearest set of stairs, at the top of which stood a skinny man with curly brown hair and a wide smile plastered on his face.

"Doctor," Amy said. "Doctor, who is that?"

"Well, there is a surprisingly small amount of people it could be," the Doctor said, speaking to her but looking at the man. "He's gotten into my TARDIS, he's not telling me how it's bigger on the inside like everyone else does on first trips, and he's got a TARDIS," he paused to look at Amy. "Of his own."

"But yours is the only one," Rory said.

"Yes," the Doctor said. "Yes, it is. But his is occupying the same time and space as ours, can't you tell?"

Amy looked around again. Where the corners of the room should have been, there was an extra plane, like another room trying to fit on top of this one but turned a few degrees too much. The coral pillars were all thick in odd places. And - she couldn't quite be sure - the console appeared to have more knobs and fiddly bits than usual.

"How?" Rory asked, glancing around, looking worried. "I mean, if yours is the only TARDIS in the universe there can't just be another one out of the blue. Can there? There can't."

"Who is that?" Amy asked again.

The Doctor looked up at the skinny, smiling man. "He's the Master."

"Oh, you recognized me, even with my new face," the Master said, trotting down the steps. "You flatter me, Doctor. But you did always know me far too well. And never well enough." There was that smile again, so self-satisfied.

"The Master?" Amy said. "Isn't that a bit egotistical?"

"Very," the Doctor said, never taking his eyes from the Master. He smiled, but there was no lightness in it. "You're dead."

The Master shrugged exaggeratedly. "Never could stay dead properly," he said. "A lot like you. There's just so much to do." He walked forward, running one hand lightly along the console. "It was high time for me to come back."

The Doctor listened, his posture relaxed, but Amy saw the confusion storming behind his ancient eyes. And fear. There was no denying it - there was fear there, too.

"Can't you smell it, Doctor?" the Master asked fervently. "Taste it? Hear it feel it need it Doctor!" Something manic flashed across his face and vanished - but not entirely. It left behind traces of hysteria in the twitch of his lips, the too-smooth movements of his body. "Through all of those roiling nebulas and the oceans and plains and lights of the cosmos, it's coming. And you need to be ready for it, Doctor. Or it'll destroy you."

"Ready for what?"

"The days to come," the Master said quietly. "The time - the time for Time Lords."