The Doctor held up a small, paperback book triumphantly. 'Look at that,' he said.

Donna Noble looked at the cover; Agatha Christie, Death in the Clouds was written in bold font, followed by a beautifully painted picture of a wasp trailing a biplane through the sky. She smiled softly. 'She did remember.'

'Somewhere in the back of her mind, it all lingered. And that's not all,' said the Doctor, excitedly, as he handed the book over to Donna. 'Look at the copyright page.'

Donna opened the book. 'Facsimile edition,' she read aloud. 'Published in the year...' she slowed, looking up at the Doctor, shock clear on her face. 'Five billion?!'

The Doctor's grin was ear-to-ear. 'People never stop reading them. She is the best-selling novelist of all time.'

Donna sighed. 'But she never knew...'

'Well, no one knows how they're going to be remembered,' said the Doctor, taking the book back from her. 'All you can do is hope for the best. Maybe that's what kept her writing.' He paused. A flicker of sadness in his ancient eyes. 'Same thing keeps me travelling.'

He then blinked, looking back at Donna. 'Onwards?'

'Onwards,' Donna agreed, his smile reflected in hers.

'Well then!' The Doctor closed the chest where Agatha Christie's book was stored and pushed it under the grate flooring. With everything back in its place, he offered Donna a hand up, then was at the TARDIS console, dancing around the controls with practised ease. 'Speaking of long-remembered authors and their books, I have got the perfect place for us to visit.' He gave Donna a lopsided grin, coming to stand next to her at the handbrake. 'Fancy a trip to The Library, Ms Noble?'

'Depends,' began Donna, 'do I need a library card?'

The Doctor's smile only grew at her teasing. He shoved the handbrake into position and the time rotor cranked into action, bobbing up and down. Still, after all these years, the wheezing and groaning of the TARDIS engines excited him. 'Think of the biggest library you can think of Donna,' he said, whizzing around to the other side of the console. 'Then forget it because it is insignificantly tiny to the library I'm about to take you to.' He grabbed the edge of the console monitor and brought it in front of him. '51st century should be perfect. Molto bene!'

'51st century?' muttered Donna, glancing over the beautiful 1920s flapper dress she still wore from Lady Edison's party. After all the running around she'd done, it was scuffed in a few places, the little orange and white bead details loosening to the point where she was afraid they might fall off. 'Should probably change then, yeah?' she asked the Doctor, already halfway over to the stairwell giving access to the rest of the TARDIS.

'Probably, yeah,' came the Doctor's absentminded reply.

'And you?'

'Hmm? What about me?'

Donna stopped at the stairwell, turning to face him. 'Are pinstripes and trainers really accepted no matter where you go? Why's it only me that's got to change?'

She waited for the Doctor's answer, but he only mumbled something about a gravitic anomaliser and Henry VIII.

'One day,' continued Donna, 'I'm gonna get you to wear something other than that daft old—Wah!' She was cut off by a loud shriek of electricity and the unexpected groan of the grate floor as it jittered beneath her; then the Doctor's loud exclamation of WOAH! and her own terrified screaming as the TARDIS began shaking violently.

Under a wave of vertigo, Donna launched herself at one of the winding coral struts nearby and hung on for dear life.

'What the bloody hell is going on!' Donna managed to shout above the screeching bells and whistles going off around her.

'Something's interfering with the TARDIS's telepathic circuits!' cried the Doctor in frustration. 'Her temporal stabiliser has gone all out of whack and the Helmic Regulator is non-functioning!' To prove his point, or maybe in a desperate attempt to get it working again, the Doctor began rapidly pumping the regulator lever to no effect.

'And all that means?!' Donna shouted, barely able to focus on the Doctor. He was a big, blurry, blobby mess of brown next to the console.

'Someone or something is pulling us through the Time Vortex at an accelerating rate. The TARDIS is—' he was cut off as the TARDIS rocked, sending out sparks from beneath the console. Donna, unable to keep her grip on the coral, rocketed forwards with a yelp and collided with the back of the jump seat. The Doctor looked over at her—a wide-eyed, terrified expression on his face that Donna had never seen before. 'If we don't slow down, the TARDIS is going to rip a hole through space-time. We'll be sucked out into the void and lost forever.'

'What do you mean lost?' Donna murmured, worriedly. She felt she should do something. Shout at him, crack a joke, or lay a comforting hand on his shoulder—anything to get that look off his face, but she wasn't given the chance as the TARDIS lurched again.

Donna stumbled backwards with a cry. Unable to keep her footing, she toppled over, hitting her head against the coral strut she'd clung to earlier, and landed hard on the floor. Unmoving.

'DONNA!' the Doctor thundered; his knuckles white from where his hands were desperately clamped around the edges of the console. He chanced a glimpse at his companion before the TARDIS unsettled again. She looked OK. No bleeding. Hopefully only a mild concussion. Not that it would matter much what condition either of them was in if they became trapped in the void for eternity!

Think, Doctor, think!

Just as he had a brilliant idea, the TARDIS swung in the other direction and began plummeting. The Doctor collided with the console, the air knocked out of him. Red in the face and struggling to breathe, his left hand fumbled for the handbrake while his right gripped the Helmic Regulator lever. Pumping it, his sneaker pressed up against the shielding module, the Doctor turned the Vortex shields up to maximum, simultaneously slamming the handbrake into the forward position.

Pleaseworkpleaseworkpleasework!

A disgusting grinding noise echoed throughout the control room as the time rotor came to a wrenching stop. The TARDIS halted and the Doctor fell to the floor, relieved. 'It stopped, it stopped,' he muttered aloud, hearts pounding furiously in his chest. He honestly hadn't thought shatterfying the shields whilst drawing the Helmic Regulator would stop the TARDIS's nose-dive through the vortex, but he was enormously glad that it did.

Getting to his feet, the Doctor pulled the monitor into view, noting the coordinates and the year. 'Just outside the Andromeda Galaxy, twenty-fourth century. Weell...' he drawled, 'for Earth, anyways. How's that Donna? Don— Oh...'

He'd forgotten she'd hit her head.

Willing himself away from the console, the Doctor crouched down above Donna. Her hand was a bit chaffed from the fall to the grating, but her head seemed fine and she didn't have a concussion. Good.

Still breathless, the Doctor would have waited for Donna to wake had there not been a knock at the door.

A serious, stricken look crossed the Doctor's features as he stood straight. Based on the sensors he'd viewed earlier the TARDIS was currently free-floating in space with no ships or life forms around for trillions of miles. Even a cloaked vessel would have been picked up on the scanner. Nobody could be out there.

Toc-Toc came a second knock.

'Who's there?' asked the Doctor, his tone curious.

There was no response.

'Answer me!' he demanded, raising his voice.

Without warning the Doctor found himself bathed in a bright, all-encompassing white light as the TARDIS doors flew open. He shielded his eyes, trying to catch a glimpse at what was infiltrating his TARDIS.

It was humanoid, decorated by several pointy bits around the head, and cloaked in a long, black robe, its shadow casting across the Doctor's face.

'Who are you?'

The robed figure did not answer. Instead, it removed an angular, box-shaped object from beneath its robe which it raised in the Doctor's general direction. Swallowing tightly, the Doctor raised his hands and took a protective step in front of Donna's prone form.

'Look, whatever it is you want, you don't have to resort to violence!' he said. 'I can help—!'

'Be silent, Time Lord.'

It was a whisper; something that didn't sound quite real to the Doctor's ears. Perhaps it was a mental projection or recording, but he knew what those sounded like and this was something... different. Something that didn't make sense to him. Perhaps it was because of how dizzy he was beginning to feel; the ache of his bones and the tiredness that was overtaking him. He suspected the blurs in his vision were no longer a result of the harsh light as the control room turned on its side.

'Do what you want with me,' the Doctor managed, swaying on his feet, 'just leave Donna alone. She has nothing to do with this, so just. Just—'

Unconsciousness claimed him.