'What is it?' asked Curnow with mild distaste, hefting the little mechanism in his hand. 'A guillotine for mice?'

'Not a bad description – but I'm after bigger game.' Floyd pointed to a flashing arrow on the display screen, which was now showing a complicated circuit diagram.

'You see this line?'

'Yes – the main power supply. So?'

'This is the point where it enters Hal's central processing unit. I'd like you to install this gadget here. Inside the cable trunking, where it can't be found without a deliberate search.'

'I see. A remote control, so you can pull the plug on Hal whenever you want to. Very neat – and a non-conducting blade, too, so there won't be any embarrassing shorts when it's triggered. Who makes toys like this? The CIA?'

'Never mind. The control's in my room – that little red calculator I always keep on my desk. Put in nine nines, take the square root, and press TNT. That's all. I'm not sure of its range – we'll have to test that – but as long as Leonov and Discovery are within a couple of kilometres of each other, there'll be no danger of Hal running amok again.'

'Who are you going to tell about this... thing?'

'Well, the only person I'm really hiding it from is Chandra.'

'I guessed as much.'

'But the fewer who know, the less likely it is to be talked about. I'll tell Tanya that it exists, and if there's an emergency you can show her how to operate it.'

'What kind of emergency?'

'That's not a very bright question, Walter. If I knew, I wouldn't need the damn thing.'

'Guess you're right. When do you want me to install your patented Hal-zapper?'

'As soon as you can. Preferably tonight. When Chandra's sleeping.'

'Are you kidding? I don't think he ever sleeps. He's like a mother nursing a sick baby.'

'Well, he's got to come back to Leonov to eat, occasionally.'

'I've news for you. The last time he went across, he tied a little sack of rice to his suit. That will keep him going for weeks.'

'Then we'll have to use one of Katerina's famous knockout drops. They did a pretty good job on you, didn't they?'

Curnow was joking about Chandra – at least, Floyd assumed that he was, though one could never be quite sure: he was fond of making outrageous statements with a perfectly straight face. It had been some time before the Russians had fully realized that; soon, in self-defence, they were prone to pre-emptive laughs even when Curnow was being perfectly serious.

Curnow's own laugh, mercifully, had much abated since Floyd had first heard it in the upward-bound shuttle; on that occasion, it had obviously been primed by alcohol. He had fully expected to cringe from it again at the end-of-orbit party, when Leonov had finally made rendezvous with Discovery. But even on that occasion, though Curnow had drunk a good deal, he had remained as much under control as Captain Orlova herself.

The one thing he did take seriously was his work. On the way up from Earth, he had been a passenger. Now he was crew.

We are, Floyd told himself, about to awaken a sleeping giant. How will Hal react to our presence, after all these years? What will he remember of the past – and will he be friendly, or hostile?

As he floated just behind Dr Chandra in the zero-gravity environment of Discovery's flight deck, Floyd's mind was seldom far from the cut-off switch, installed and tested only a few hours earlier. The radio control was mere centimetres from his hand, and he felt somewhat foolish to have brought it with him. At this stage, Hal was still disconnected from all the ship's operational circuits. Even if he was reactivated, he would be a brain without limbs though not without sense organs. He would be able to communicate, but not to act. As Curnow had put it, 'The worst he can do is swear at us.'

'I'm ready for the first test, Captain,' said Chandra. 'All the missing modules have been replaced, and I've run diagnostic programs on all circuits. Everything appears normal, at least on this level.'

Captain Orlova glanced at Floyd, who gave a nod. At Chandra's insistence, only the three of them were present for this critical first run, and it was quite obvious that even this small audience was unwelcome.

'Very well, Dr Chandra.' Ever conscious of protocol, the captain added quickly: 'Dr Floyd has given his approval, and I have no objections myself.'

'I should explain,' said Chandra, in a tone that clearly conveyed disapproval, 'that his voice-recognition and speech-synthesis centres have been damaged. We'll have to teach him to speak all over again. Luckily, he learns several million times faster than a human being.'

The scientist's fingers danced over the keyboard as he typed out a dozen words, apparently at random, carefully pronouncing each one as it appeared on the screen. Like a distorted echo, the words came back from the speaker grille – lifeless, indeed mechanical, with no sense of any intelligence behind them. This isn't the old Hal, thought Floyd. It's no better than the primitive speaking toys that were such a novelty when I was a kid.

Chandra pressed the REPEAT button, and the series of words sounded once again. Already, there was a noticeable improvement, though no one could have mistaken the speaker for a human being.

'The words I gave him contain the basic English phonemes; about ten iterations, and he'll be acceptable. But I don't have the equipment to do a really good job of therapy.'

'Therapy?' asked Floyd. 'You mean that 'he's – well, brain-damaged?'

'No,' snapped Chandra. 'The logic circuits are in perfect condition. Only the voice output may be defective, though it will improve steadily. So check everything against the visual display, to avoid misinterpretations. And when you do speak, enunciate carefully.'

Floyd gave Captain Orlova a wry smile, and asked the obvious question.

'What about all the Russian accents around here?'

'I'm sure that won't be a problem with Captain Orlova and Dr Kovalev. But with the others – well, we'll have to run individual tests. Anyone who can't pass will have to use the keyboard.'

'That's still looking a long way ahead. For the present, you're the only person who should attempt communication. Agreed, Captain?'

'Absolutely.'

Only the briefest of nods revealed that Dr Chandra had heard them. His fingers continued to fly over the keyboard, and columns of words and symbols flashed across the display screen at such a rate that no human being could possibly assimilate them. Presumably Chandra had an eidetic memory, for he appeared to recognize whole pages of information at a glance.

Floyd and Orlova were just about to leave the scientist to his arcane devotions when he suddenly acknowledged their presence again, holding up his hand in warning or anticipation. With an almost hesitant movement, in marked contrast with his previous swift actions, he slid back a locking bar and pressed a single, isolated key.

Instantly, with no perceptible pause, a voice came from the console, no longer in a mechanical parody of human speech. There was intelligence – consciousness – self-awareness here, though as yet only on a rudimentary level.

'Good morning, Dr Chandra, This is Hal. I am ready for my first lesson.'

There was a moment of shocked silence; then, acting on the same impulse, the two observers left the deck.

Heywood Floyd would never have believed it. Dr Chandra was crying.