CITY AT WORLD'S END.

by CHRISTOPHER BULIS.

Prologue.

The force of the impact totally destroyed the asteroid and came close to splitting the tiny moon in two. In a fraction of a second, kinetic energy of motion was converted to heat, light and a scattering of X-rays. The combined flash was visible across half the stellar system.

A crater five kilometres deep and almost eighty wide was blasted out of the moon's surface. Fifty thousand cubic kilometres of rock were converted into an incandescent plume of vapour and semi-molten fragments and ejected into s.p.a.ce at a velocity too great for the slight gravity of the moon to ever draw it back. In time it would form a ring about the moon's parent world.

During the days following the collision the outward effects of the cataclysm gradually subsided. The scar of the glowing crater that stretched across half a hemisphere cooled below red heat. New mountain ranges thrust up by the impact settled into equilibrium. The shock waves reverberating through its interior faded away, leaving only the steady whisper of thermal contractions within the surface rocks.

So the moon continued tumbling on through s.p.a.ce but no longer along the same course it had followed for the previous hundred thousand years. The impact had reduced its velocity, and in obedience to the laws of motion and gravitational attraction its...o...b..tal path changed.

The long fall had begun.

Chapter One.

The City.

'I don't suppose you've any idea at all where we've landed, Doctor?' Barbara asked the old man in the black frock coat.

There was an edge of weary impatience in her voice.

The Doctor remained bent over the console, throwing switches and tapping dials, the cool white light of the control room gleaming off his flowing silver-white hair. 'The readings are not as clear as I might wish...' he said absently, 'but it seems we are a few thousand years beyond your time, Miss Wright.'

'Well, whenever it is, it doesn't look very prepossessing,'

Ian Chesterton observed.

The TARDIS's monitor camera had completed a full rotation and once again displayed the first image they had seen after landing: slowly billowing fog almost obscuring a long curving chest-high wall topped by a wire mesh screen. The ground between the TARDIS and the base of the wall was covered in blackish mud dotted with puddles. The view had been much the same to either side. Behind them was the blank expanse of a taller dirt-streaked concrete wall that stretched as far as the eye could see.

'It does look pretty dismal, doesn't it?' Susan agreed, her bright intent face at odds with her words. 'But according to the instruments the composition of the air and the temperature are both fine.'

'So now I suppose you want to go outside and take a look around?' Barbara said.

The Doctor straightened up, hooked his thumbs under his lapels and thrust out his chin. 'And why should I not, pray?'

'Firstly, because there doesn't seem to be anything of interest there and secondly, because it's not where we want to be.'

'May I remind you,' the Doctor said testily, 'that I am not operating a taxi cab service. I promised to return you to your proper location in s.p.a.ce and time as soon as it was practicable, but I refuse to leave this place without making at least a cursory examination. Who knows what strange and wonderful things we might find Out there... just beyond that wall, perhaps?'

'And who knows what might find us,' Ian pointed out.

'You and Miss Wright are at liberty to remain inside the TARDIS if you wish, Chesterton,' the Doctor said dismissively, 'but I am going outside.'

'And me, Grandfather,' Susan said quickly.

The Doctor smiled benignly at her, good humour returning mercurially to his features. 'Thank you, my dear. Let us leave our unadventurous friends to their own devices. But perhaps we'd better wear our coats. It does appear to be rather damp out there.'

'I'll fetch them,' said Susan, stepping lightly over to the bentwood stand in the corner.

Ian caught Barbara's eye and she gave a little helpless shrug. They had been Susan's teachers back on Earth in 1963, but now, as her strange origins became more apparent, she was growing away from them. To outward appearances and in some mannerisms she was still a teenage girl, but Ian sensed a personality of great strength and boldness developing within her.

They said nothing as the Doctor donned his long cloak and m.u.f.fler, while Susan put on a stylish raincoat and cap she had brought with her from England. The Doctor threw a switch on the console, the TARDIS's heavy outer doors swung smoothly inwards, and he and Susan stepped outside.

'There really isn't any point in arguing with the Doctor, is there?' Barbara said ruefully. 'I sometimes wonder whether even after all this time he resents the way we came aboard, and is determined to take us back home by the longest route he can find as a punishment.'

Ian smiled. 'You know him. He never minds where he ends up.' He checked the monitor screen which showed Susan and the Doctor examining the muddy ground. 'Still, there doesn't seem to be anything dangerous outside this time.'

Barbara saw the expression on his face. 'You're getting as bad as he is. You don't have to keep me company if you want to go outside.'

'I wasn't staying just to keep you company,' Ian protested.

'But as we're not going anywhere until the Doctor's ready anyway, we might as well take a look.'

Barbara sighed. 'I suppose it wouldn't hurt to get some fresh air and stretch our legs...'

As they stepped out of the narrow outer door of the TARDIS, which externally retained its disconcerting resemblance to a twentieth-century British police call box, Ian tasted the air. It was cool and fresh enough except for a faint tang of stale soot.

Their feet sank into a thick layer of crusted black mud.

Barbara grimaced. 'I should have worn wellingtons.'

The largely featureless wall behind the TARDIS proved to belong to one side of a round structure, broken only by narrow louvered windows and a solid metal utility door. Mounted on its roof was a heavy latticework girder mast that rose high above their heads. Extending from its sides were several oddly shaped mesh panels and dishes which Ian took to be aerials.

The other wall appeared to surround the building entirely and was separated from it by the strip of level, muddy ground.

Ian and Barbara picked their way across the mud avoiding the puddles. The Doctor, still crouching beside Susan, looked up at them in satisfaction.

'Ah, so you've decided to join us after all, have you?

Good.' He indicated the ground. 'What do you make of this, eh?'

'It's mud,' said Barbara.

'No,' the Doctor beamed. 'If you examine it closely you will find it is layered ash and soot. Clearly there have been several fires close by in the recent past.'

'I suppose n.o.body comes here very often,' Barbara said, looking about her. 'I can't see any other footprints.'

Ian made a cautious circuit of the open ground around the building, which was about twenty yards in diameter. 'There are no other doors,' he reported when he returned, 'or any opening in the outer wall. Just more fog beyond it.'

'Maybe there's a tunnel,' Susan suggested.

Together the four of them walked with squelching steps across to the outer wall and peered through the mesh screen into featureless swirling opalescence.

'Well, I don't call that particularly wonderful,' Barbara said, pointedly glancing at the Doctor.

But even as she spoke the wind was strengthening. An orange disc of a sun appeared in the grey sky, growing brighter by the second. The fog shredded and thinned about them. Suddenly a dramatic vista crystallised out of the haze.

'Don't you, Miss Wright?' the Doctor retorted triumphantly.

'Of all the places to land us,' Ian said with a chuckle, 'you had to pick the top of a skysc.r.a.per!'

They were looking out over a great city of similar buildings. As the fog rolled away they saw hundreds of towers thrusting graceful spires up towards the clouds. These were linked by an intricate web of enclosed tubes and aerial roadways that spanned the artificial canyons formed by the buildings' stepped walls of gla.s.s and stone. Streamlined vehicles, looking like scurrying beetles from high above, were speeding smoothly along the open ways.

'Can you see any people?' Ian asked after a minute.

The Doctor had taken a pair of folding opera gla.s.ses from the recesses of his coat and was peering about intently.

'Not at the moment,' he said, 'but then the inclement weather has no doubt been keeping them inside.'

Barbara pointed to their right. 'The city seems to stop short in that direction. Do you see between those buildings... is that a wall?'

The Doctor turned his gaze in the direction she indicated.

'It is indeed a wall of considerable height,' he reported. 'I can see a flat-topped tower built into it... there is some smaller structure mounted on its roof which I cannot identify.' He swung his gla.s.ses from side to side. 'The wall continues as far as I can see. Perhaps, like medieval cities, this one is entirely enclosed.'

'What's that beyond it?' Ian asked, narrowing his eyes in the silvery-grey light.

'A range of mountains,' the Doctor reported, 'running along at the back of the city...' He swung about. '...Which appears to be built on a promontory jutting out into a sea or at least a sizeable lake. I can make out a wide sh.o.r.eline running away to the horizon. Hmm. There is some object of considerable size lying part of the way along the sh.o.r.e. It does not seem to be natural... this is most annoying, I cannot quite make it out. Susan, dear... will you run back to the TARDIS and fetch the telescope?'

Susan was back in a minute carrying a long naval-style bra.s.sbound telescope of antique design.

'I left some very muddy footprints on the floor, I'm afraid,' she said apologetically.

The Doctor rested the telescope on top of the parapet wall and focused on the object on the sh.o.r.e.

'Most extraordinary,' he murmured.

'Don't keep us in suspense, Doctor,' Ian said. 'What is it?'

'See for yourself, Chesterton,' said the Doctor, relinquishing his position.

Ian focused the device and gave an exclamation. 'A flattened cylinder...a huge vessel of some kind, I think.

Perhaps a submarine? It's split half open down one side. No, surely it's too big to be a submarine. A crashed airship, perhaps?'

'Don't let your imagination be limited by the capabilities of your own time,' the Doctor warned as Ian gave up his place so that Susan and Barbara could look. 'Who knows what devices the people of this world may be capable of building?'

'With those exposed ribs it looks rather like a beached whale,' Barbara said.

'An inappropriate if picturesque simile,' the Doctor replied. 'However, the object has certainly been badly damaged.' He tapped his chin. 'What fate befell it, I wonder?

Unless it is a very recent tragedy, why has it not been salvaged?'

They made their way slowly around the parapet examining the sprawling cityscape. The boundary wall seemed to be continuous.

'What's it meant to keep out?' Barbara wondered.

The towers coming into view became steadily taller.

Evidently the one they had landed on was situated near the city's outskirts. Now they were facing towards the centre, which had previously been hidden by the roof building.

Suddenly the Doctor halted: 'My goodness! How remarkable.'

Standing in the very heart of the city was a structure that dwarfed all the others around it. It rose in a series of graceful tiers and flowing curves and even through the hazy air it gleamed metallically. Beside it was a huge latticework tower of girders connected to the silvery form by numerous extended bridges and boom arms.

'It looks a bit like one of those rockets they launch from Cape Canaveral,' Ian said breathlessly. 'But this must be over a hundred storeys high.'

The Doctor, peering through the telescope, said: 'The upper sections of what I take to be support fins are just visible over the tops of the intervening buildings. It does indeed appear to be a rocket and launching gantry.' He then added with unexpected solemnity: 'Truly a ship worthy of the city giving it birth.'

'What was that about picturesque similes?' Barbara chided him gently.

'I was employing metaphor, Miss Wright, not simile,' the Doctor retorted. 'And there are times when it is fully justified.'

'But why build such a huge rocket right in the heart of the city?' Susan wondered. 'Launching it would cause terrible damage unless it had a counter-gravity drive.'

'But the streamlining suggests a high launch velocity,' the Doctor pointed out. 'It may be propelled by simple nuclear transfer reactions.'

'But would they risk the pollution that would cause?'

'They may have mastered the use of the stable transuranic elements,' the Doctor speculated. 'Or perhaps a pulsed fusion system with a magnetically contained thrust.'

Ian was beginning to feel left out of the conversation and saw a glazed look in Barbara's eyes. Back at Coal Hill School on Earth he'd taught Susan science, yet the terms and concepts she was using so casually were far beyond his understanding.

He coughed. 'Excuse us, but does it matter how it's powered?'

'You're quite right, Chesterton,' the Doctor agreed unexpectedly. 'The question of propulsion can be put aside for the time being. First we must determine its intended purpose.

Something momentous I'm certain.'

His eyes were sparkling and Ian could almost feel the enthusiasm crackling from him. The Doctor began walking briskly back towards the roof building with Susan at his side carrying the telescope.

'Just a minute,' said Barbara, 'where are you going?'

'There must be a way down through this building to the first of those roadways,' he said. 'We may be able to utilise the transport system to reach the ship.'