'And this was - what, four hours ago? How long does it take to perform an autopsy?'

'Well, yes, I see what you mean, but there has been a war going on, you know, Doctor. I didn't think - '

'Right. You didn't think. Well, that's about par for the course, Brigadier.'

'Now look here, Doctor, I did my best - '

'Well I'm afraid it wasn't good enough!' snapped the Doctor.

'You've endangered the whole of England by your actions - perhaps the whole of the world.'

There was a short silence. Then Jo said quietly, 'So what do we do now, Doctor?'

The Doctor put his hands on his hips, looked around him. 'The Xarax can grow very fast if they want to, given enough sources of food. They could be well advanced already. We need to return to England as soon as possible.'

The Brigadier nodded briskly. It made a change for the Doctor to give out instructions that could be understood, let alone ones that he thought were a good idea. 'Right,' he said. 'All we need to do is find Rashid's people and radio Rabat. They'll come and pick us up.'

'We might not need to find Rashid, sir,' said Yates, who was still holding his binoculars. 'I think one or two of the Harriers got away.'

He pointed at two distant specks moving fast, close to the ground.

The Doctor turned and stared for a moment, then said, 'Those aren't Harriers, Captain. In fact, if I'm not mistaken -' he broke off, raised his voice. 'Quickly!' He turned to Tahir Al-Naemi. 'Have your people got any transport?'

Tahir hesitated, glanced at Vincent, then said, 'We have a dozen jeeps on the mountain road. But I don't think we'd get to them before - ' He gestured at the moving specks, which were already visibly closer.

'Blue-black markings, sir,' said Yates suddenly. He had the binoculars to his eyes. 'I don't recognize the nationality.'

'That's because they haven't got a nationality, Captain,' said the Doctor. 'They're Xarax.' He paused, put a hand on Jo's arm. 'I suggest we make a run for it.'

Twenty-Four.

FJo ran with the others, stumbling once or twice over the rough grey pebbles. Her body felt strange: her hands and feet were numb, as if she'd been given a local anaesthetic.

It must be the shock, she thought. Her stomach heaved again at the memory of what Vincent had done to Benari. She'd never seen anything so horrible. She still couldn't believe that Vincent had done it. He had never made any secret of being a killer; he had never made any secret of the fact that he was proud of it. But she hadn't expected him to just do it like that, just kill someone. Not even Khalil Benari.

They were almost at the road now. Jo glanced over her shoulder, saw the sunlit plain littered with the corpses of Xarax. Above it, the two jets were clearly visible now. She could see strange f.l.a.n.g.es and protrusions that belonged to no human aircraft design.

She reached the road, scrambled up the bank, saw the jeeps parked in the deep shadow of an overhang a couple of hundred metres away.

The Doctor was already halfway there: he looked back at her, shouted something she couldn't hear over the whistle of the approaching jets.

She glanced over her shoulder again, saw the two delta-winged shapes less than half a mile away. She realized that she wasn't going to make it.

An arm took hold of hers, pulled her forward, helped her to run.

She smelled sweat and gun oil, saw the familiar dark, close-cropped hair. Vincent. Saving her life. She wondered if he enjoyed that as much as he enjoyed killing people.

There was an explosion ahead of her, and Vincent flung her to the ground. Rock scratched at her hands, but the pain was curiously muted, unreal. When she looked up, her blood oozed from her hands in long, sticky drops, brownish rather than red.

There was something wrong with that. But what?

'Jo! Come on!'

Something screamed overhead, deafening her, and she was on her feet again, running. She could see Vincent ahead, firing his gun at the receding jet. Beyond him the jet exploded, a huge ball of yellow fire.

'Someone needs to go to Kebir City,' the Doctor was saying.

'They've obviously got a nest there - that's where the jets are being controlled from. It's vitally important that it's disabled.'

'I'll go,' said Mike Yates, getting into one of the jeeps. Jo looked at him, realized that she hadn't said how pleased she was to see him, that she hadn't even said h.e.l.lo.

'I'll go with you,' she said. 'I've seen a bit of Kebir City. I might be able to help.' She got into the jeep after Mike, smiled at him. 'h.e.l.lo, by the way.'

Mike grinned back at her, but said, 'I'm not sure you should be going with me. It's not going to be safe on that road. Besides, the Kebirian authorities want to arrest you for murder.'

'It's not safe anywhere,' said the Doctor. 'And I very much doubt the Kebirian authorities exist any more.' He was already getting into the jeep behind theirs, starting the engine. 'Look after her, Mike,' he called. The jeep sprang away in a clatter of small stones.

Vincent appeared from a cl.u.s.ter of his men, jumped into the back seat of their jeep.

'I will come with you. I know Kebir City; besides, it is my jeep, eh?'

Jo struggled to think of a reason why he shouldn't come. She didn't want him to come. She didn't want to see him kill anyone. But before she could speak, there was an explosion of sound above them and the iridescent blue-black carapace of a Xarax jet flashed past. A gust of hot, dust-smelling air hit Jo in the face.

'Go, go, go!' yelled Vincent. Mike hit the starter, and the jeep was in motion, tyres grating against the rough surface of the road.

Jo frowned as they gathered speed. There was something she should have told the Doctor - something vitally important - There was an explosion, a long way behind them. Jo looked round, saw a jeep plunge off the road and roll out of sight amongst the rocks.

Vincent swore: Mike hit the accelerator. The jeep lurched wildly as it headed down the track, throwing Jo from side to side. Grit stung her eyes. What was it she should have told the Doctor?

She looked at the brown blood oozing like honey from her swollen hands, and tried to remember.

The explosion rocked the jeep. The Brigadier heard a crash of metal, looked over his shoulder and saw the jeep at the tail of the convoy roll off the road. One of the others stopped; someone fired into the air, tracking the jet as it swept overhead.

There was an explosion of yellow fire as the jet disintegrated.

Pieces of chitin arced through the air.

'Another hit, Doctor,' observed the Brigadier. 'Those things don't seem to be very bullet-proof.'

'Considering that they're using organic materials to travel at twice the speed of sound, Brigadier, it's a miracle they don't explode when you're not shooting at them.' He glanced over his shoulder at the wreckage and the thinning smoke. 'A shame really. It's a good idea, theoretically speaking.'

The Brigadier hastily turned his attention to the jeep's radio, before the Doctor could start getting technical.

'Trap seventy-four. Trap seventy-four. Come in, please.'

This time, when he pressed the receive key, there was a faint, crackly response... seventy ... you, Lethbridge-Stewart?'

'Of course it's me, Rashid. What's your position? Over.'

'Ten kilometres north ... target. We are surrounded. I ... waiting, over.'

'Please repeat, seventy-four. What force is surrounding you?'

... Kebirian Army! At least ... brigades with ... '

The Brigadier didn't quite believe it. 'You mean you've been sitting on your backsides for the last half-hour while we've been shot down, run around and bombed? Hadn't you noticed that the Kebirians have gone a bit quiet, man?'

'... but I don't understand,' replied the French-accented voice. There was a crackly pause and for a moment the Brigadier thought he'd lost the signal. Then it resumed with: ' ... your position and ... meet us at ... '.

The Brigadier looked at the Doctor. 'Where are we, Doctor?'

'How should I know, Brigadier?' Infuriatingly enough, the Doctor seemed to be enjoying himself, steering the jeep at near impossible speeds along the twisting road, throwing clouds of dust and grit behind him. They seemed to have lost the others.

'Seventy-four, where will you pick us up? We're currently on the mountain road heading south.'

' ... meet you at Al Gohi. Please repeat back, over.'

'Confirmed. Al Gohi. Over and out.' The Brigadier leaned back in his seat, heaved a sigh of relief. 'You can slow down a bit, Doctor. It looks like our problems are over for the time being.'

But the Doctor's face was serious. 'I don't think so, Brigadier,' he said. 'Look behind you.'

The Brigadier looked, and his heart sank as he saw the distant blue-black shapes of Xarax helicopters moving slowly across the plains behind them.

For a moment Jo thought the helicopters might be human-made, then she saw the legs folded beneath them, the scorpion tails, the shuttered Xarax eyes.

'Mike!' she shouted; but Yates had already seen them, and so had Vincent. He was standing in the back seat, sighting his gun on the nearest alien as it approached.

'Hang on, Vincent,' said Mike. 'They're not taking any notice of us.'

It was true: the Xarax flew past, keeping low, throwing up clouds of dust and grit.

'They're probably going to pick up the honey from the nest, so that it won't go to waste,' said Jo.

'How do you know that?' said Vincent, his gun still trained on the 'copter as it fell behind them.

Jo frowned. 'I'm not sure. I was - linked up to the nest while I was in there. I think I've sort of picked up the way the Xarax think.' She could hear it now, drumming away in the back of her brain: - honey honey honey sweet sweet good to be honey to be sweet honey sweet sweet good to be honey to be sweet - - She jumped violently as the cold metal of Vincent's gun touched the skin of her neck.

'You have become like them?'

'No!' said Jo.

Mike pushed the gun away. 'What are you playing at?' he snapped.

'Jo is - '

'It is possible for these aliens to imitate people,' said Vincent calmly. 'Jo could be an imitation, sent to trick us.'

'I'm not an imitation!' protested Jo. 'I'd know if I was!' But even as she spoke she remembered the dream image, the other Jo walking away. The Brigadier had said there'd been one copy of her. Could she be another? Was it possible? She looked at her hands again, at the sticky, brown, honey-like blood. It was just an infection, the product of what the nest had been trying to do to her. Wasn't it? 'At least, I think I'm not,' she muttered aloud.

The cold metal of Vincent's gun touched her neck again. 'And I think we ought to make sure, eh?'

Jo felt her body begin to shake.

'Now wait a minute,' said Mike. 'I've already met the imitation Jo, and I can a.s.sure you that this one is the real thing.'

Vincent didn't move the gun. 'And what are the differences between the imitation and the real thing?'

Mike hesitated, then said, 'She didn't speak to me the way she usually does - she seemed to spend a lot of time staring at the horizon. And she wore a kind of perfume.'

Vincent leaned forward; Jo felt the gun track across her shoulder blades. Her skin crawled.

'A sweet perfume?' asked Vincent. He took Jo's shoulders and pushed her sideways, so that her body collided with Mike's. 'A perfume like this?'

Mike stamped on the brakes, throwing both Jo and Vincent forward. The jeep slewed across the road, came to a halt in a cloud of dust.

When the dust settled, Jo saw to her horror that Mike had drawn his gun.