Are you sure this is the only way of dealing with the Cybermen?'

Cutler raised his hand to stop the guards. 'Yes, old man. As they're about to attack us us, it's the only way I know...'

The Doctor's voice sounded slightly higher pitched than usual, a little quavery with age. "There is another way.' He waited until he had everyone's attention,'.. to wait! Eh, Dr Barclay?'

'Wait!' echoed Barclay, confused. 'I'm afraid I don't understand you.'

'Well,' snapped the Doctor, 'think, man, think.' He looked around irritably. 'You all call yourselves scientists, don't you? Can't you see it isn't only the Earth that's in danger.

Mondas itself is in far greater danger-otherwise why would the Cybermen want to visit Earth? All they have to do, surely, is simply to sit tight and wait until Mondas is replenished by our energy.'

He paused for a moment and looked around him with a little of his old authority.

Finally, Cutler nodded. 'O.K., you've got a point. But so what?'

'Don't you see,' continued the Doctor, 'all the Earth's stock of energy could be too much for this new planet. It could burn itself up, shrivel away to nothing. All we have to do is to wait.'

Cutler intervened sharply. 'Wait until your Cybermen friends get here and take over this planet? No, we're not going to wait, Doctor. We'll accelerate accelerate the process a little. the process a little.

Mondas will burn up a little sooner-that's all.'

The Doctor's strength seemed to ebb again at Cutler's words, and he shook his head. 'That would be a mistake. A nuclear explosion on Mondas would certainly release a terrible blast of radiation. Enough to destroy all life on the part of the Earth facing it.'

He grasped the console, his face white, and shook his head as if trying to collect his thoughts. Anxiously, Polly took his arm-but he shook her off.

'It might even turn into a sun-a super-nova. It would certainly destroy your son's capsule.'

'That's a risk we'll just have to take. As far as the capsule is concerned, we're going to fuse the bomb and hit Mondas when my son's...o...b..t has taken him to the far side of the Earth.'

The old Doctor shook his head in despair. His fingers nervously tapped his lapels.

Barclay, who had been listening intently to the Doctor, stepped forward. 'General, there is no guarantee of success even if we use the Z-bomb.'

'I'm not arguing,' said Cutler. 'Just do it.'

'Sir,' the radio technician's voice cut in abruptly, 'they're on the move again!'

As Cutler started to walk across to the console, he turned to the guards who were standing by the time travellers. 'O.K., you can take them away now.'

'The girl too?' one of the guards asked, his eyes fixed on Polly.

Cutler looked back briefly, smiled, and shook his head. 'No, she's no menace. I guess you can leave her here.'

As the guards started to lead Ben and the Doctor away, Polly stayed by them, still grasping the Doctor's arm. 'I'm coming too.'

Ben turned quickly and shook his head. 'No you're not, d.u.c.h.ess, you're staying here.'

'But the Doctor?' pleaded Polly.

'I'll look after him. Work on Barclay instead. Get him to see sense,' added Ben in a whisper.

Polly let go of the Doctor's arm and halted irresolutely. Before she could answer, the two time travellers were led out of the room by the guards.

Cutler turned back from the radar screen. 'There's no time to lose. Ready, Barclay?'

Barclay met his gaze for a minute, and then nodded. 'You'll have to be present at the fusing, General. Dyson can't do it without your being there.'

The General nodded. 'O.K., Mr Dyson, let's get on with it.' As he turned to go, Polly stopped him. 'Can I stay and help?'

Cutler looked at her. 'How do you think you can help, girl?'

'I could make tea or coffee... or something.'

Cutler shrugged. 'All right. I guess we could all do with some coffee.' He turned back to the radar technician. 'Keep track of those Cybermen. I want to know the moment an attack is imminent.'

10 Prepare to Blast Off

'Doctor! Doctor!' Ben was worried sick. The Doctor seemed to have aged even in the few minutes that they had been locked in the cabin. The guards had thrust them into a room belonging to a couple of the base technicians. It resembled a ship's cabin-with two bunks set one above the other, a built-in wardrobe, chest of drawers, a desk and chair. The Doctor had fallen asleep on the lower bunk almost immediately.

Was it Ben's imagination, or had the Doctor's hair gone a shade whiter and finer during the last few hours? His skin, which looked as transparent as old parchment, was stretched tightly over his prominent cheek bones.

Ben shook his head dejectedly. He began to speak to himself as usual-a habit he had picked up during long night watches at sea.

'Better let the poor old geezer sleep. He looks all done in.' He looked around the cabin, then got up, walked over to the door and tried the handle. Locked. Parts of an electric iron were scattered about the table -one of the technicians had obviously been repairing it. Beside it was a small tool kit-pliers, wire cutters, screwdrivers, etc. etc. Ben eagerly picked up the tools, and started work on the door lock. Ben eagerly picked up the tools, and started work on the door lock.

After a quick examination, however, he gave up in disgust and flung the tools back on the desk. 'What's the use? They didn't have locks like this back in the 1970s.'

He sat down dejectedly in a chair, and began to rock it backwards. Suddenly, something on the ceiling caught his eye.

Just above one end of the upper bunk, a large square grille-part of the air conditioning system-had been let into the ceiling.

Ben measured it with his eye. How large was it? Taking a sudden decision, he sprang to his feet, picked up one of the screwdrivers and, carefully avoiding the sleeping Doctor, scrambled on to the upper bunk.

Dyson and Cutler entered the silo room. Cutler looked around him curiously.

Although as base cornmander he made a monthly tour of inspection, the silo room was not a place to linger in. In spite of the many nuclear technology courses which Cutler had attended, he had little real understanding of how to a.s.semble and launch a nuclear weapon. 'All a General needs to know is the location of the "fire" b.u.t.ton,' was how he usually explained away his ignorance. It was his job to make the decisions-and up to the scientific egg-heads to understand the technology that made it all possible.

The oblong-shaped room, which had been painted a neutral mid-green, contained a complex array of pipes colour-coded in red, blue, and yellow. Along one wall ran a bench containing electronic equipment and several large cylinders connected by pipes to the bomb itself. A large hatch led through to the tall, two-storeyhigh Demeter rocket in the firing tube. From there, the bomb could be placed directly into the 'payload' area.

However, it was the Z-bomb itself which caught-and held-their attention.

It looked like a smooth cylinder with rounded ends, approximately sixty centimetres across by one hundred and twenty centimetres long. Over the Z-bomb hung a steel lifting cradle, which was connected to the ceiling by thin chains. Around the top half of the room a gallery with a railing projected three feet out from the wall. It was reached by a ladder from the floor of the silo room, and provided access to the various system control panels set at intervals around the room.

Cutler, followed by Dyson, walked over to the bomb, and stared down at it for a moment. Various labels, stencilled in bold white letters which read ISC PROTOTYPE A, had been fixed to the grey surface. At one end of the bomb another label read No 1 FUSE LOCK, and at the other No 2 FUSE LOCK.

Cutler listened to the hiss of the vacuum pumps. The metal beneath him vibrated to the powerful hum of the large dynamos.

'O.K., Dyson, hurry it up. What are we waiting for?'

'We've last minute checks, sir.' He pointed to the gallery where two engineers with clipboards were checking the dials and ticking off a column of figures.

Cutler nodded and stepped back. 'The sooner we get this baby loaded and into the rocket, the sooner our problems will be solved.'

Dyson, his head averted, nodded and mumbled something. Cutler smiled. 'I'm glad you at least agree with me.'

Dyson looked up anxiously. 'If we get this away, do you think we stand a chance, sir?'

'I don't work out chances in advance. It doesn't pay. As far as I'm concerned, we've no alternative.'

'But the Doctor could have been right-it might be safer to wait.'

Cutler removed his cigar. 'Wait nothing. History is littered with guys who waited.

And where did they get? Nowhere! '

'But what about the radiation effects? I mean, nothing is known... this bomb could...'

He stopped. Cutler noticed his hands were shaking.

'You know, I've never heard you say so much before. What's the matter, Dyson- chicken?'

Dyson shook his head quickly and looked down at his clipboard. 'No, not exactly.'

To his surprise, Cutler put a hand on his shoulder. 'Come on, man, admit it. When it comes to the Z-Bomb, I'm chicken-we all are! But I'm also scared for my son. That's why we're going to send this thing off.'

He looked up at the engineers. 'Come on, fellas. Hurry it up, will you, time's short.

You want to book a good seat in the Control Room ready for the fire-cracker display, don't you?'

The men grinned down at him and nodded.

Dyson felt more confident now. 'O.K., we can start now, sir.'

Cutler watched as Dyson and the two engineers started working on the bomb. First, they opened two lockers-widely separated at either end of the room-with special keys, and took out identical cylindrical fuses. Positioning themselves at opposite ends of the bomb, they began to screw them firmly into place.

This done, the rotary click switches at the ends of the fuses were rotated in readiness for the number combination which Dyson now stood in readiness to dictate. He glanced from one engineer to the other. 'Ready? Right! Seven, two, five...' The deadly combination, number by number, was being set..

In the main control tracking room, Barclay was leaning anxiously over the communication technician's shoulder. 'Well?'

The R/T technician shook his head. 'Still can't raise Lt. Cutler, sir.'

'Keep trying. Tell me the minute you hear from him.'

Barclay walked back to the console, his brow furrowed, thinking deeply. He became aware of Polly standing by his desk. She had placed a tray with coffee, tea, and soft drinks right in the middle of his papers.

'Get that out of here,' he snapped.

'I'm sorry.' She indicated the tray : 'Tell me what you want first.'

'Oh! ' Barclay looked at the display before him: 'Coffee, I suppose.'

'Are you trying to get in touch with General Cutler's son?' Polly asked, as she poured out his coffee.

Barclay shook his head irritably. 'Just keep your mind on the coffee, will you?'

Then, realising what he had said, he looked up at her: 'I'm sorry, that was very rude of me.' He smiled wryly. 'You must be scared stiff with all this happening.'

Polly nodded. 'If Mondas turns into a sun and pours out deadly radiation, how much would it affect us?'

Barclay looked away as if reluctant to tell her the worst. 'I don't know-of course it might not affect us at all.'

'That wasn't what you said just now.'

Barclay shrugged despairingly: 'Let's face it, no one's completely sure what could happen.'

'But you do have some idea?'

'I suppose,' Barclay looked at her almost guiltily, 'the radiation could affect us.

There's bound to be some-and probably considerable, loss of life. The Earth's vegetation will suffer very badly over a period of years.'

Polly, who had been drawn before by Barclay's gentleness, drew back a little. 'And you're prepared to let this take place?'