Completely ignoring Merdeen's instructions, he stared in fascination at the towering form of the robot, scarcely noticing the two white-clad acolytes bobbing about in front of it.

'Welcome,' said Drathro. 'I have long been waiting for this day. Welcome at last!'

'You've been expecting me?'

'For centuries. I am Drathro, an L3 Robot.'

'Then I fear you are under a slight misapprehension, Drathro,' said the Doctor. 'I only decided to come here yesterday.'

'You are not from Andromeda? Then where are you from?'

'Gallifrey, originally. But I travel a lot.'

'I have heard of Gallifrey. An advanced civilization.'

'In some ways,' said the Doctor.

'I apologize for my error.'

'That's all right,' said the Doctor generously. 'Even immortals make the odd mistakes every few millenia.'

'I am not immortal.'

'Ah! Well, the locals seem to think you are.'

The robot gestured towards the two white-clad figures.

'These are my a.s.sistants, Tandrell and Humker. You will work with them.'

'Will I? Why?'

'Because I command it.'

'I see,' said the Doctor thoughtfully. 'And obviously you're a robot who's used to getting your own way.'

Humker and Tandrell crowded round the Doctor, prodding and poking at him. 'This is remarkable,'

said Humker.

Most impressive,' agreed Tandrell.

'Even its texture has organic warmth,' said Humker amazed.

'Do stop prodding me, there's a good fellow,' said the Doctor.

Drachm boomed, 'The Doctor is not a robot. He is an organic from an advanced civilization.'

Tandrell was amazed. 'An organic?'

'We have not met an organic since we pa.s.sed the Selection,' said Humker.

'Aha!' said the Doctor. 'I knew you two hadn't ended up for lunch.'

'Explain,' said Tandrell.

The Doctor waved him away. 'Never mind.' He looked up at Drathro. 'What is this work you want me to do?'

'Is this relevant testimony, Valeyard?' asked the Inquisitor testily. 'We seem to be straying from the point.'

'The testimony is circ.u.mstancially germane, My Lady,'

insisted the Valeyard. 'It forms part of the prosecution's case that the Doctor introduces a disruptive and corrupting influence wherever he goes.'

'Sheer poppyc.o.c.k,' said the Doctor briskly.

The Valeyard's voice quivered with anger. 'If the Doctor had not visited Ravolox, the whole chain of events we are witnessing would never have been set in motion.'

'How can the boatyard make that claim?' shouted the Doctor. 'What might or might not have happened is purely speculative.'

'That is for me to decide, Doctor,' said the Inquisitor.

Quite clearly, she was not amused. 'May I remind you that the charges you face are grave indeed?'

'I have only to look at the graveyard to see that, My lady,' said the Doctor, going rapidly from bad to worse.

'Your puerile attempts at flippancy are not appreciated in this Court, Doctor. Proceed Valeyard.'

The screen came to life once more.

With the help of Tandrell and Humker, the Doctor had removed the casing from an enormous control console and was now elbow-deep in the complex circuitry inside.

Drathro hovered impatiently over him. 'Have you found the fault yet?'

The Doctor looked up. 'Give me a chance, I've just started.'

'The black light system is indicating incipient failure,'

boomed Drathro.

'I can see that,' snapped the Doctor. 'They don't last forever, you know.'

'I am trained only in installation and maintenance,' said the robot.

The Doctor was buried inside the console again. 'What?

Oh, very useful too, that's where the money is.'

'I have trained these humans to study the problem, but they make no progress,' said Drathro almost plaintively.

'Well, black light is very tricky stuff, Drathro...'

'I have a learning capacity, but my process of ratiocination are strictly logical. Organics sometimes eliminate such steps.'

The Doctor went on working. 'It's called intuition,' he said absently.

'Your first task will be to restructure the system.'

'Now just a minute,' protested the Doctor. 'Black light just isn't my field.'

'Then you will make it so - or die!'

In the Courtroom the Doctor leaped to his feet. 'I protest!'

The Inquisitor said wearily, 'What now?'

'Yes, now!'

'I mean what are you protesting about about Doctor?' Doctor?'

'I am charged with interference, yet it is obvious to a blind sneelsnope that I am working under duress.'

The Inquisitor considered. 'That does seem a valid point. What is the relevance of this presentation, Valeyard?'

'If the accused had not interrupted, My Lady, the point I wish to make would have become obvious.'

'Then I apologize for my outburst, My Lady,' said the Doctor handsomely.

'As Your Ladys.h.i.+p is aware, unlike the Valeyard I am unfamiliar with court procedure.'

For the first time the Inquisitor mellowed a little. 'The Court accepts your apology, Doctor,' she said graciously.

'Valeyard, you may proceed.'

The screen lit up once more. This time it showed the village of the Free people. They were building a pyre.

Peri, Dibber, and most particularly Glitz, watched unhappily as the eager hands of the villagers piled brushwood around the foot of a sinisterly charred wooden stake.

They laughed and chattered excitedly as they worked.

For the villagers a public burning was the equivalent of a stoning to the underground dwellers - one of the few bits of entertainment in an otherwise dull existence.

'What a terrible waste,' said Dibber.

'You're telling me,' said Glitz, the intended victim, touched by his taciturn colleague's concern.

'No, I meant the wood,' explained Dibber. 'If I was handling this execution I'd go for a bullet in the back of the neck. Much more economical.'

'He has a point,' said Peri.

Glitz glared reproachfully at them. 'Of all the snivelling screeds to be stuck with in my moment of need I have to get you two!'

'Depressing innit,' said Dibber.

Their guards prodded them back towards the prison hut. There was still a lot of work to be done on the pyre.

The Doctor straightened up. 'Sorry, Drathro, there's not a lot I can do down here.'

'I order you to work.'

'You can play the slave-driver all you like, but the fault doesn't lie down here at all. There must be a malfunctioning collection aerial up there on the surface.

I'll just pop up and take a look at it for you.'

The robot barred his way. 'You will remain here and proceed with your task.'

'I think you must have fluff in your audio circuit,' said the Doctor reprovingly. He looked round the equipment-crowded control room. 'What's all this stuff for, anyway?'

'It provides Drathro with his energy source,' said Humker.

'It was intended also to maintain the three sleepers till they could be returned to Andromeda,' said Tandrell.

'The three sleepers?'

The Doctor was beginning to piece the story together.

Drathro had been installed by an expedition from Andromeda, designed perhaps to save some of the natives of the planet from the effects of the approaching fireball, by setting up an underground survival system. But something had gone terribly wrong.

'The sleepers are dead now,' said Drathro. 'The relief s.h.i.+ps failed to arrive.'

Three Andromedan astronauts in suspended animation, thought the Doctor. Waiting for a back-up expedition that never came. But the fireball had been less devastating than had been feared, and life had gone on, on the surface and underground...

But that was all in the past, thought the Doctor. An equally terrible crisis now menaced them in the present.

'Now, listen,' said the Doctor urgently. 'If this black-light power failure is allowed to get any worse, we'll all be as dead as your three sleepers.'

Humker stared at him. 'Why?'

'Because there's going to be a most enormous explosion, that's why! An explosion in which everyone in your precious underground colony will be destroyed!'