'No,' replied the Doctor confidently. 'Unless, of course, it found another way in.'

'Such as?'

'Your mind.

Tegan looked confused. 'The dream?'

'Not quite.' The Doctor turned and fixed her with a sudden, piercing stare. 'Do you recall the fault in the telepathic circuits?' Tegan nodded. 'I thought it just blew a fuse or something.'

'Psionic feedback, I said. Something was trying to force its way past the TARDIS defences.'

'Using my mind?' Nyssa sounded appalled, but the notion seemed to galvanise her. Tegan could tell Nyssa's brain was already working through the consequences with her customary logic, sloughing off the earlier panic.

The Doctor was nodding vigorously as he paced around the console room. 'Your subconscious mind, to be precise, probably while you were asleep.'

'But all this occurred when I woke up from the nightmare.'

'Which is right when the telepathic circuits went phutt!' phutt!'

realised Tegan.

'Yes,' said the Doctor thoughtfully, leaning on the console. 'Whatever it was must have hitched a ride from your dream state, Nyssa. Interesting!'

'But what could do that?' Tegan sounded alarmed. Is it still here?'

'Very unlikely. The short circuit would have prevented any real temporal incursion. But it might be possible to trace the original telepathic signal...' The Doctor began to operate the controls on the panel in front of him, his face a sudden mask of concentration.

Tegan felt the old, familiar tingle of excitement in her stomach: part fear, part antic.i.p.ation. But this time, she decided, she was going to be ready for it. She was going to help.

'Of course,' the Doctor was saying as his fingers travelled across the console, 'it might be a bit tricky with a system malfunction, but Nyssa, try initiating a repair program, would you?'

Instantly, Nyssa stepped up to the opposite side of the console and began operating the switches. Tegan felt a minute p.r.i.c.kle of envy, watching them work together like a team. It was almost as if Nyssa had become the Doctor's a.s.sistant. But then Nyssa had a strong science background, which Tegan supposed must be an advantage.

'The fault locator won't identify the relevant subroutines for a repair program,' complained Nyssa.

The Doctor hesitated, then said, 'Never mind, we'll try a short cut.' He hurried around to join her. 'If I can tap into the residual energy in the telepathic circuits, the TARDIS may be able to calculate an exact point of origin.'

'Won't that be dangerous?'

'No more than leaving whatever it was that tried to invade the TARDIS via your dream free to try again.'

'But you'll have to link directly with the TARDIS telepathic circuits.'

'I thought they were damaged!' protested Tegan.

Nyssa said, 'It's a terrible risk!'

'Nonsense,' the Doctor declared. 'All I have to do is tune my thought waves into the TARDIS artron signature, and...'

he placed the flat of his hands onto two metallic plates located on one of the console panels, and then closed his eyes.

'I don't like the sound of this,' said Tegan flatly. 'What's he trying to do?'

Nyssa examined the various readouts and displays before her. 'He's trying to align the TARDIS telepathic processor unit to the co-ordinate panel. If he can -'

There was a violent crackle like a firework going off and the Doctor jerked back from the console, hitting the wall behind him heavily. There, he slid down until he lay sprawled across the floor.

Tegan ran across and knelt down by him. He looked pale and stunned but otherwise unhurt.

'Is he all right?' asked Nyssa.

'He's out cold. What happened?'

They looked back at the control console, where wisps of smoke were drifting from the telepathic circuits. As they watched, the gla.s.s column at the centre of the console began to slow in its rhythmic movement.

'The TARDIS is materialising,' said Nyssa.

The central column came to a rest with a soft chime. For a moment all they could hear was the gentle hum of the TARDIS around them.

'We've landed.'

The question is,' said Tegan, 'where?'

The Doctor reached out to touch the cave wall. 'Curious rock structure. Is it crystalline?'

'Not quite, although you'd be forgiven for thinking so,'

Stoker said.

The rock was smooth and gla.s.s-like, black but with a hint of a deeper, darker green. It had an almost organic quality that Stoker still found unsettling.

'I think we're the first human beings to set foot on Akoshemon's moon.' she went on. 'It's still a bit of a closed book.'

'What are you looking for?'

Stoker hadn't been expecting such an abrupt change of subject, so she paused just long enough to take another drag on her cigar before answering. 'Fortune and glory, isn't that what they say? Fortune and glory.'

'Straight to the point,' admitted the Doctor, 'but hardly informative.'

They were walking back through the cave system, away from the area where the explosion had occurred. The air was a little better here, but it had the dank and closed smell of compacted soil and granite the galaxy over. There were electric lights fixed to the glossy walls of the pa.s.sages connecting the main caves, bright and yellow but horribly unflattering. Everyone instantly gained a pasty, sick looking complexion.

'Somewhere inside this rock is the remains of a forgotten civilisation,' Stoker told the Doctor. 'I'm hoping to dig up something very, very old and valuable, or something very, very pretty and valuable. But preferably both.

'And therefore doubly valuable.

'You got it.'

Stoker's men were busy in the ancillary cavern moving heavy equipment and storage crates. There were only five of them, and all but one was human. The Doctor glanced at Vega Jaal and then turned back to Stoker.

'Forgotten civilisation?'

'There won't be much left except dust and bones. Maybe a few trinkets. Something that can give us an inkling of the kind of people who used to live in these parts.'

'When you put it like that, it doesn't sound very lucrative,'

the Doctor commented.

'Depends what you're interested in,' said Stoker. She stubbed out the cigar against the rock wall. 'My sponsors just love love bones and dust and old trinkets.' bones and dust and old trinkets.'

'They'd have to. This looks like a very difficult operation.

You're a long way from any major star system, there are no obvious signs of any ancient civilisation that I've noticed, and...'

She stopped him with a look that was as cool and impenetrable as the stone that surrounded them. 'And?'

The Doctor met her stare levelly. 'And I've never met an archaeologist yet who preferred high explosives to patient work with a trowel and brush.'

Stoker gave an irritated snort. 'You ask a lot of questions.'

'I'm just curious.

'Lucky you're not a cat, then.' Stoker turned and called out to one of her men. 'Hey, Bunny!'

Bunny Cheung turned and Stoker beckoned to him. The non human with the owl-like eyes and sharp features followed Bunny over.

'Our new friend here doesn't believe this is an archaeological dig.' Stoker told him.

Bunny grinned. 'What does does he think we're doing here?' he think we're doing here?'

'I'm not sure. A holiday, perhaps?'

'You were using high explosives,' the Doctor pointed out.

'Or had you forgotten how we came to meet in the first place?'

'Maybe you think we're gun-runners or something,'

smirked Stoker. 'Smugglers. Pirates. Terrorists, even.'

'We have the necessary credentials,' said Bunny Cheung. He reached into a wide pouch hung on his left hip and produced a coloured plastic doc.u.ment. 'This gives us authority, from the Department of Alien Antiquities at the University of Tyr itself. We're here to uncover the secrets of the Akoshemon system.'

The Doctor flipped through the permit and handed it back. 'I beg your pardon. Please forgive me, but I'm still a little confused. Probably a touch of sh.e.l.l shock, I expect.'

Stoker eyed him carefully. He was hiding something behind all that courtesy; she was about to say something when the Doctor turned to Vega Jaal and started talking to him in a strange, fluting dialect punctuated by clicks and glottal stops.

Jaal replied in kind, inclining his head politely, almost deferentially, to the Doctor.

'What was all that about?' asked Stoker. Her irritation with the Doctor had given way to bemus.e.m.e.nt.

'I was introducing myself properly to Vega Jaal, here.

That is to give him the correct form of address, of course.

The people of Vega have a venerable tradition of honour and respect for proper names.'

Stoker glanced at Jaal. 'Do they really?'

'Oh, yes,' the Doctor said.

'You've been to Vega, then?'

'Actually, no.'

'You spoke to him like a native.'

'I have a flair for languages.

'That might come in useful, if we hit on any ancient hieroglyphics or runes.

'Is that likely?'

Stoker shrugged. 'Who knows? We're still digging.'

They moved off, the Doctor following Stoker again, leaving Vega Jaal and Bunny to carry on with their work.

There was some muted conversation among the men behind them and then a burst of laughter.

'It must be very useful having a Vegan on your team,'

said the the Doctor. 'Vega has produced more mining engineers and pot-holers than practically any other planet in the galaxy. Doctor. 'Vega has produced more mining engineers and pot-holers than practically any other planet in the galaxy.

Just the thing for an archaeological dig.'

'You said it.'