'No, Doctor!' called Nyssa in alarm, trying to catch up with him. 'It's too dangerous!'
'There's no other way!'
'What are you going to do?' asked Stapley, trying to get a word in edgeways.
'The Doctor's going to materialise round the Master's TARDIS,' said Nyssa, horrified at the risk.
'You know what happened before!' Tegan had her own nightmare memories of those Chinese puzzles, from when she first stumbled into the TARDIS.
The Doctor would not be stopped. 'There's no time for anything else,'
he called from the cabin door.
But there was no time for anything at all.
'We're too late,' groaned Nyssa, as the dreaded clattering reached them from across the mudflat.
Then there was only one Concorde left parked on the frozen tundra.
The Master had gone.
'With the power of the Xeraphin, the Master will be invincible,'
declared Nyssa.
And we're stuck, thought the Doctor. 'Without the bits he stole from my TARDIS, we can only travel in this time zone,' he explained to the others.
'We're marooned?' asked Tegan in disbelief.
'I'm afraid so.'
Before anyone could think of anything to say, another whirring sound filled the air. They all looked up to see the shape of Golf Victor Foxtrot rematerialise a short way from their own aircraft.
The Doctor was not a man to take pleasure in the misfortunes of others, but a broad smile lit up his face. The Master was stuck as well.
The Master flung open the door of his Concorde TARDIS and glared at the Doctor. 'Devious to the last,' he hissed.
'Technical hitch?' Butter wouldn't melt in the Doctor's mouth as he smiled innocently at his enraged enemy.
'Your substitution of the time lapse compressor, for the temporal limiter,' accused the Master.
'That's the way it goes,' the Doctor chided infuriatingly, 'if you will steal other people's property.' Leaving the Master on the point of apoplexy, he swung round to Nyssa. 'What's he talking about?' he whispered.
'Have you been tampering with my TARDIS?'
'Of course not.'
'Just imagine what would have happened if I had tried to go forward with the temporal limiter patched
into the time lapse compression circuit...'
Captain Stapley felt like a schoolboy who had got his best friend into trouble. He coughed politely. 'Doctor, I think I can explain.'
'You, Captain?' said the Doctor, very surprised if he could.
'When we were in the TARDIS, I swapped some of the parts round.
Thought it might put a spanner in the works.'
The Doctor's eyes were already twinkling.
'Stupid really.' the Captain apologised.
Grinning from ear to ear, the Doctor grasped Stapley by the hand.
'Stupid?' he shouted. 'It was brilliant!'
The Master was straining to hear what was going on below. The Doctor smiled up at him. 'Your prospects seem rather limited, Master.'
Through the Master's mind raced a thousand and one exquisite tortures he would like to inflict on the Doctor. He restrained himself from telling the Doctor all about them. Unfortunately, the ball, just for the moment, was in the Doctor's court. 'I can still operate my TARDIS,'
he replied.
'Yes. But such a limited range.'
The Doctor had him there. 'Very well. What are your terms?'
'You free the passengers,' demanded the Doctor, 'we have access to both aircraft, and you return all the components of my TARDIS that are no longer necessary for the normal functioning of your machine.'
'And what will you give me?'
'The temporal limiter,' bargained the Doctor.
It was a hard decision for the Master. His old enemy would be able to escape. But he needed the temporal limiter, and with the Xeraphin life force in his TARDIS the Doctor would not outwit him for much longer ...
The Master slammed the door.
'Has he agreed?' asked Stapley.
'We'll know in a moment.'
'Look!' shouted Andrew.
The Corinthian column had appeared a few yards away.
'There's the real Concorde,' said Tegan, pointing to the aircraft with its torn wing and dislocated engine pod.
'The Master's accepted,' cried Nyssa as Captain Urquhart's passengers began to emerge from the marble fluting.
'Captain,' said the Doctor to Stapley who was staring in disbelief at the improbable disembarkation, 'I need your aircraft ready for takeoff as soon as possible.'
Stapley pulled himself together. 'Andrew, Roger ... We'll need to measure the length of that runway.' They all went across to examine the stretch of frozen mud.
'You two stay here,' the Doctor ordered Tegan and Nyssa. He walked slowly to the Master's TARDIS. The Master stood in the doorway, in his arms a pile of vital equipment. Not a word was spoken. The Doctor took the pieces one by one. The two Time Lords stared impassively at each other. 'You seem to have mislaid the quantum accelerator.' The Doctor was the first to break the silence.
'Not at all, Doctor. You shall have it when you give me the correctly programmed temporal limiter.'
Their distrust was mutual.
The Doctor turned and hurried back to where his TARDIS was waiting in the Concorde hold.
Bilton and Scobie attacked the frozen ground around the four-wheel bogey of Victor Foxtrot's starboard undercarriage. The earth was like concrete and they were soon sweating profusely. At least they were warmer than Tegan who stood beside them shivering, waiting to help take the weight of the wheel, once the soil had been removed from under it.
'Doctor, I'll need an external power supply for the startup, 400 cycles, 115 volts,' Captain Stapley called into the control room.
'Very well, Captain.' Nyssa prepared to run a line from the TARDIS.
'Easy now.' Tegan helped Roger and Andrew lift the second wheel clear of the support. They stood for a moment getting their breath back. Just as well the soil was so hard and icy, thought Tegan, or the remaining two wheels might have slipped into the excavation, bringing the whole aircraft down on top of them.
'Right,' said Roger Scobie, 'you and Andrew roll those wheels across to Alpha Charlie. I'm going on board Victor Foxtrot to rip out a reduction valve and some trunking from the air-conditioning, then I'll strip the components for our own undercarriage.'
Tegan and Andrew raised one of the wheels and began to trundle it towards the other Concorde. I've been here before, thought Tegan, with a sudden flash of deja vu; then realised how similar were the wheels of the airliner to Aunt Vanessa's sports car.
The Doctor soon replaced the components that had been pilfered by the Master.
Nyssa watched him scramble round under the console. She was uneasy.
'Doctor, you haven't got the
quantum accelerator back from the Master.'
And he hasn't got the temporal limiter,' replied the Doctor as he slid out the essential module from where it had been hidden by Captain Stapley. 'The idea is to keep him waiting until we're ready to take off.'
Nyssa was terrified at the idea of trying to get airborne again in Concorde. With the quantum accelerator in place, the TARDIS would be working as well as ever. Why couldn't they all go back in that?
'I need the TARDIS to deal with the Master,' said the Doctor.
'How?'
'I'm thinking about it,' replied the Doctor enigmatically.
Ice-cold fluid dribbled over Roger Scobie's hands and down his sleeve as he removed the damaged brakeline. The replacement was standing by; in a few moments the undercarriage would be repaired.
Beneath the port inner engine Tegan helped Andrew with a bundle of tubing which the copilot was connecting to the valve of one of the tyres. 'Two and three engines have to be started with an external air supply,' he explained. 'One and four then start internally.'
'Undercarriage fixed!' A grubby but cheerful Scobie slipped into the flight-deck.
'Well done, Roger.'
Nyssa's head appeared in the door behind him. 'External power all right, Captain?'
'Yes.' Captain Stapley started to get out of the left-hand seat. 'Tell the Doctor we're ready, will you, please?' Nyssa scurried back towards the cargo hold. 'Roger, I want to do a final walk-round of the aircraft while we're waiting for the Doctor.' The Captain scrambled from the cockpit with his engineer.
The Master watched all the activity like a hawk. He knew the Doctor was playing for time, but he would give him so much leeway ... and no more. He strode towards Tegan.
Tegan, kneeling over the wheel, saw the black figure out of the corner of her eye. She turned; the Master loomed over her.
'I am impatient to leave this place. Tell the Doctor I require the temporal limiter immediately, or I shall start to eliminate your passengers.' He held the deadly black weapon between his fingers as casually as if it were a cigarette holder. But Tegan knew that his promise was no idle threat.
'Captain StapJey says the aircraft is ready,' announced Nyssa, returning to the TARDIS control room.
'Good,' said the Doctor as he tinkered with the temporal limiter.
'Another few minutes.'
Tegan ran in, breathless from the gymnastics involved in reaching the TARDIS. 'Doctor, hurry up!' she shouted. 'The Master's getting trigger-happy out there.'
'Then we'd better not keep him waiting.' The Doctor picked up the temporal limiter.
'Looks fine, Roger,' said the Captain as he examined the repaired undercarriage.
Roger was as pleased as punch at his make do and mend, but was apprehensive at the impending takeoff.
They all iooked at the mudflat stretching away to the horizon, and quietly said a prayer. 'No knowing what'll happen going over that ground at two hundred knots,' muttered Scobie.
'What happens when we get airborne?' asked Bilton, looking on the bright side.
'Up to the Doctor isn't it?'
The Doctor walked the short distance to the Master's TARDIS. The Master was waiting for him.
'The temporal limiter,' demanded the Master.
'The quantum accelerator,' insisted the Doctor.
Neither trusted the other a millimetre. The Master guardedly revealed the Doctor's accelerator. The Doctor allowed a glimpse of the Master's limiter. There was a fumbling, mutual snatch and grab. The deal was done.
'Shall I say au revoir, Doctor?' The Master oozed venomous charm.
The Doctor turned his back dismissively on his arch enemy and returned to the plane. Hardly had the Master, with a dark chuckle, entered his TARDIS than the column dematerialised.
By now none of the crew batted an eyelid. 'I suppose he could end up anywhere in the universe,' said Captain Stapley.
'Heathrow, actually.'
The Doctor's casual announcement caused consternation.
'He's virtually running in a new TARDIS,' he went on to explain. 'To check out the temporal dimensions he'll need to track back the line of the time contour.'
Andrew Bilton was appalled at what the Doctor had just allowed to happen.
'He'll land up in London with the nucleus on board?'
'Yes.'
'It's a disaster!'
'Quite right.' The Doctor couldn't agree more. 'Shall we go on board?'
All around them dazed passengers were returning, once again, to their senses.
'The punters are your responsibility, Tegan,' shouted Stapley, making a quick escape to the main door. 'When you get them on board, stand by on those tyres.'
Just my luck, thought Tegan. My first job as a stewardess. She tried to forget how dirty and sweaty she was and approached the passengers with a radiant smile on her face. 'Ladies and gentlemen, we do apologise for the delay ...' The words flowed like syrup. 'Your flight to Heathrow is now ready for boarding. Would you proceed to the aircraft immediately.'
The Doctor soon had the quantum accelerator back in circuit. He stood up from the console looking very pleased with himself. Nyssa couldn't understand why. 'The Master will get to Earth before us,' she fretted.
'Not with my temporal limiter in circuit,' the Doctor reassured her.
'It won't work?'
'Of course it will. You don't think I could fool the Master do you?' He started to make his way out of the TARDIS and towards the flight deck.
Nyssa recognised the glint in his eye. She smiled. 'Mind you,' said the Doctor, 'there is an inhibition factor inherent in the programming.'
'What does that mean?'
The Doctor grinned. 'We get to Heathrow first.'
Tegan felt very lonely out in the cold beside the two wheels, with everyone else strapped in their seats waiting for takeoff. She looked up at the flight deck window, hoping for the sign to release the compressed air.
But with such a hazardous launch before them, the pre-flight checks were more vital than at any well-equipped international airport.