All at once a deafening howl ran through the freighter and it tilted violently, sending them all skidding across the sloping deck and into the rear wall. The gigantic craft vibrated as if it were going to shake itself to pieces and the noise was so loud that Adric could not hear what Berger and Briggs were screaming at him, although their faces were almost touching his. All three tried to crawl back up the steep slope
towards the console, but the deck was far too slippery and an overwhelming centrifugal force seemed to be crushing them down.
'I can't . . . I can't move . . .' Adric gasped, fighting for breath.
As the dreadful howling reached a climax, they stared helplessly up at the warning lights that flashed urgently all over the console, until the irresistible force drove their heads against the cold metal floor.
In the hold, the Cybermen had just begun to gain ground, trampling heedlessly on their fallen as they surged up the stairway and onto the walkway above. As the freighter went out of control, the troopers were thrown forward against their makeshift barricade; but the Cybermen were completely disorientated: they staggered and slid all over the place and then lay immobilised, their electro-gyroscopic balancing mechanisms utterly ineffective. The troopers saw Scott's mouth opening and shutting in his contorted face as he tried to shout orders to them, but no sound penetrated through the cataclysmic roaring and buffeting of the shuddering spacecraft...
The Doctor, Nyssa and Tegan watched in silence as the image of the freighter faded and reappeared and faded again on the viewer in the TARDIS control chamber.
'What's happening, Doctor?' Nyssa exclaimed, as the flickering grew faster and faster.
In a few seconds the freighter's image had disappeared altogether.
'Where's it gone?' Tegan cried, her voice breaking with tension.
'The freighter seems to have entered a warp spiral,' murmured the Doctor mysteriously. 'It's going backwards.'
The Cyberleader raised his blaster. 'You will follow, Doctor,' he ordered.
The Doctor's eyebrows shot up. 'Follow?' he snorted. 'Where?'
'Follow them...' the Cyberleader rasped threateningly, 'You will rematerialise the TARDIS on board the freighter.'
'That's quite impossible!' the Doctor protested, as the image of the huge craft reappeared on the screen for a second and then promptly faded again. 'I've got nothing to lock on to. The freighter's co-ordinates are randomly fluctuating - that's why it keeps fading.'
The towering automaton emitted a sharp, oily sigh. 'You will do as I command, Doctor.'
The Doctor shrugged. 'I've already told you...' he stalled.
Tegan glared defiantly at the Cyberleader. 'Well, if the freighter's going backwards now - the Earth must be safe,' she butted in.
The Doctor glanced at the instruments on the console and then shook his head regretfully. 'I'm sorry, Tegan, although the freighter is spiralling backwards in
time
, I'm afraid it's still following the same
spatial
vectors,' he pointed out quietly.
On the viewer, the freighter reappeared faintly.
'Towards Earth . . .?' Tegan asked lamely. The Doctor nodded.
The Cyberleader bubbled with satisfaction. 'Excellent, Doctor, Earth will therefore be destroyed long before it ever existed in the form you have known it,' he purred.
Tegan turned to the Doctor, tears welling in her eyes. 'Is that true?' she murmured incredulously.
'It is entirely possible...' the Doctor admitted ambiguously.
Just then, the freighter's image had stabilised on the screen and it was now sharply in focus again. Far beyond it, among the brilliant background of stars filling the rest of the viewer, a tiny bluish-white disc had appeared and was slowly growing larger.
'Earth...' the Doctor whispered, almost reverently.
Speechless, Nyssa and Tegan watched the beautiful, serene planet glowing in the sunlight.
'Excellent. Hold this position, Doctor,' the Cyberleader ordered, with a hiss of anticipation. 'We shall observe the impact from here.'
Studiously avoiding his young friends' accusing stares, the Doctor gazed at the screen, his hands thrust deep into his jacket pockets. His fingers eventually closed round something sharp and metallic which had been lying there forgotten: the gold-rimmed star awarded to Adric for Mathematical Excellence. Every now and then, the Doctor glanced out of the corner of his eye at the console displays which showed how far back in time the freighter was taking the TARDIS as it hurtled inexorably towards the Earth.
Gradually, the faintest of smiles began to flicker around the Doctor's mouth...
With the memory of the freighter's ominous death-howl still ringing in their ears, Adric, Briggs and Berger hauled themselves groggily to their feet as the cumbersome ship slowly righted itself again and the vibrations died away.
'I feel as if I've been walked on by an entire army!' Briggs complained, following the other two over to the console. 'What happened?'
'We accelerated into a time spiral,' Berger exclaimed, quickly checking the displays. 'We've travelled backwards in time...' she added in astonishment.
'But that's impossible!' Briggs laughed, after a stunned silence.
'Don't you believe it!' Adric said, tackling the solution of the second logic code on the main computer.
At that moment Scott ran onto the bridge, followed by his three surviving troopers who formed a battered and exhausted semicircle round the entrance, their blasters aimed at the walkway outside.
'That was some bump!' Scott panted. 'What happened?'
Briggs sank into her command seat, staring apprehensively at Adric and Berger who worked feverishly away at the computer. 'Don't even ask,' she sighed, in a drained voice. She punched a series of buttons in the arm of the seat and a brilliant star-field flashed onto the main navigation monitor. In the very centre of the screen glowed the Earth. 'Anyway it hasn't made the slightest difference,' she muttered hopelessly, gesturing up at the screen. 'We're still bang on course.'
Adric frowned hard at the long sequence of numbers rapidly appearing on the computer display. Then he darted over to the code racks attached to the side of the navigation system and swiftly revolved the discs on the second set. There was a hum followed by a pause and then a sharp click.
'That's it. The second logic code should be released now!' he cried, waving excitedly across to First Officer Berger.
Berger immediately responded at the controls. There was an anxious silence while she checked her instruments. Meanwhile Scott joined his troopers on guard at the entrance, listening for the merest hint that the Cybermen had recovered from the freighter's temporary upheaval.
At last Berger clapped her hands. 'We've come out of warp propulsion mode!'
she announced delightedly. 'It's working, Adric!'
Adric wiped the sweat from his eyes. 'Only one more code to crack,' he grinned, returning to the computer terminal.
Suddenly Scott swung round. 'I think they're coming...' he warned. The troopers backed away from the entrance a little.
Briggs stood up. 'There's nothing more we can do,' she said, striding across the bridge to the emergency escape-pod hatch. She removed her glove and inserted her thumb into the identification lock. 'Abandon ship!' she ordered.
'This is your planet that's in danger you know!' cried Adric accusingly as he crouched over the computer keyboard, frantically trying to solve the last of the three codes.
'I am well aware of that, young man,' Briggs snapped icily, 'but in a few minutes from now we shall enter Earth's gravitational field and we are still fixed on a direct collision course.'
With a soft buzzing sound the emergency airlock opened.
'There's still time to crack the third code,' Adric protested. 'It's much more complex, I admit, but...'
'Abandon ship!' Briggs repeated, raising her voice in a kind of swooping falsetto.
Adric glanced at the monitor. The Earth was looming larger and larger. Berger came over and gently took him by the arm. 'Adric, you've done all you can,' she said.
Reluctantly, Scott ordered his troopers into the airlock. 'Hurry, lad,' he urged, as Adric resisted Berger's persuasive grasp.
'Just one more minute . . . please . . . I know I can do it!' Adric pleaded.
'That's an order!' Scott insisted.
Adric allowed himself to be led across to the airlock where Captain Briggs was ushering everyone through the hatch. She stood aside, gesturing to Adric to join the others in the escape capsule while she cast a final glance around the bridge she had commanded for so long. As he entered, Adric's sharp eye noticed the irreversible initiation control fitted into the wall at the capsule end of the airlock.
When Briggs eventually stepped into the capsule, Adric slipped out past her, tapping the initiation button as he went. Before Briggs could react, the airlock doors had started to close. Adric waved at the startled and horrified faces and just caught a glimpse of Briggs's severe face as she mouthed 'Good luck' at him a split second before the airlock sealed itself shut between them.
'Don't worry. I'll be all right!' he shouted.
Alone on the deserted bridge, Adric ran across to the computer and resumed work on the fiendishly complicated calculations. Above his head, the Earth now almost entirely filled the monitor. 'I can do it... I can do it... I must do it...' he murmured over and over again, as if he were uttering some kind of magic incantation.
So engrossed was he that he failed to hear the sinister shuffling and hissing sounds coming closer and closer along the walkway. In his excitement he had forgotten all about the Cybermen...
Nyssa watched the viewer with bated breath as the tiny silver capsule slowly pulled away from the huge dark hull of the freighter. For a moment she was filled with hope.
'What is it?' she murmured.
Tegan moved beside her and clasped her hands anxiously together. 'Adric?'
she whispered, turning expectantly to the Doctor.
'My secondary taskforce is evacuating the freighter,' boomed the Cyberleader.
'We shall complete the destruction of any surviving systems or life-forms on Earth following the explosion of the freighter.'
The Doctor frowned at the images of the capsule, the freighter and the Earth on the viewer. 'Oh, I wouldn't be too sure about that,' he retorted, glancing significantly at his two friends as he drew his hands out of his pockets and clasped them firmly behind his back. 'It may interest you all to know that we have reversed our time co-ordinates by some sixty-five million years.'
The Cyberleader emitted a hot, rancid hiss and rapidly scanned the instruments on the console as if trying to check the truth of the Doctor's startling announcement.
'Big deal, Doctor,' Tegan sniffed.
'Just think about it,' the Doctor continued earnestly. 'Remember the fossil dinosaur bones in the cavern?'
'And the reason the dinosaurs died out so suddenly!' Nyssa added excitedly, pointing to the viewer screen.
'So what?' Tegan shrugged impatiently, more concerned with the fate of Adric than the history of the dinosaurs. 'Everybody knows that the Earth collided with some kind of...' She stared at the viewer wide-eyed for several seconds, her jaw dropping.
'The freighter?' she exclaimed with a gasp. '
That's
the "asteroid"?'
The Doctor nodded. 'It is inevitable now. The anti-matter containment vessel will burst open on impact, with a colossal explosion,' he explained, with a reassuring smile. 'The history of your planet is secure after all. Thanks to the Cybermen!'
The Cyberleader rounded on the Doctor with a menacing rasp. 'You lie, Doctor...' he roared, stamping across the chamber and looming over the smiling Time Lord.
The Doctor backed away very slowly. 'Not at all. You have lost. The Earth is safe and the Congress will proceed as planned - in approximately sixty-five million years' time!' he cried, with a mocking laugh, spreading his clenched fists wide in an expansive gesture of defiant satisfaction.
At that moment, the small radio lying on the console bleeped urgently and Nyssa snatched it up.
Scott's voice crackled faintly from the speaker. 'Scott to the TARDIS... Scott to the TARDIS...'
'This is the TARDIS,' Nyssa hurriedly replied, 'we have Cybermen on board and...'
Before she could say any more, the Cyberleader had wrenched the radio out of her slender hand.
Scott's voice crackled on: 'We've managed to escape from the freighter, but I'm afraid Adric is still aboard...'
The Lieutenant's words abruptly ceased as the Cyberleader's enormous hand crushed the radio into a mess of wires and transistors and dropped the debris onto the floor.
'So Adric's still trapped,' Tegan gasped in a choked voice, her eyes brimming with tears as she stared up at the image of the freighter on the viewer. 'We've all failed him.'
The Doctor had been smiling ironically at the mangled remains of the radio, filled with contempt for the Cyberleader's puny gesture of superiority. 'I fear that the Cybermen have failed yet again,' he said quietly.
The Cyberleader swept Nyssa aside with a savage thrust and advanced on the Doctor with his blaster directed straight at the Doctor's head. 'A temporary setback to our plans, Doctor,' he hissed, 'but you will not be in a position to celebrate any victory against us.' The massive automaton stopped a metre away from his old adversary, the deadly blaster only centimetres from his victim's face. 'For you the end has come, Doctor...'