'What about Leningrad?' Smiley asks, from his desk, while he jots the occasional note.

'Nineteen fifty-three to six.'

'Yes, Connie?'

Connie is in her wheelchair again. She blames the freezing month, and that toad Karla jointly.

'We have a Brother Bretlev, darling. Bretlev, Ivan Ivanovitch, Academician, Leningrad faculty of shipbuilding, old-time China hand, devilled in Shanghai for Centre's China hounds. Revolutionary warhorse, latterday Karla-trained talent-spotter trawling the overseas students for likely lads and lasses.'

For the burrowers on the Chinese side - the yellow perils - this intelligence is new and thrilling, and produces an excited crackle of chairs and papers, till on Smiley's nod, di Salis lets go his head and takes up his narrative once more.

'Nineteen fifty-seven returned to Shanghai and was put in charge of a railway workshop -'

Smiley again: 'But his dates at Leningrad were fifty-three to fifty-six?'

'Correct,' says di Salis.

'There there seems to be a missing year.'

Now no papers crackle and no chairs either.

'A tour of Soviet shipyards is the official explanation,' says di Salis with a smirk at Connie and a mysterious, knowing writhe of the neck.

'Thank you,' says Smiley and makes another note. 'Fifty-seven,' he repeats. 'Was that before or after the Sino-Soviet split, Doc?'

'Before. The split started in earnest in fifty-nine.'

Smiley asks here whether Nelson's brother receives a mention anywhere: or is Drake as much disowned in Nelson's China as Nelson is in Drake's?

'In one of the earliest official biographies Drake is referred to, but not by name. In the later ones, a brother is said to have died during the Communist takeover of forty-nine.'

Smiley makes a rare joke, which is followed by dense, relieved laughter. 'This case is littered with people pretending to be dead,' he complains. 'It will be a positive relief to me to find a real corpse somewhere.' Only hours later, this mot was remembered with a shudder.

'We also have a note that Nelson was a model student at Leningrad,' di Sills goes on. 'At least in Russian eyes. They sent him back with the highest references.'

Connie from her iron chair allows herself another interjection. She has brought Trot, her mangy brown mongrel, with her. He lies misshapenly across her vast lap, stinking and occasionally sighing, but not even Guillam, who is a dog-hater, has the nerve to banish him.

'Oh and so they would, dear, wouldn't they?' she cries. 'The Russians would praise Nelson's talents to the skies, course they would, specially if Brother Bretlev Ivan Ivanovitch has snapped him up at University, and Karla's lovelies have spirited him off to training school and all! Bright little mole like Nelson, give him a decent start in life for when he gets home to China! Didn't do him much good later though, did it, Doc? Not when the Great Beastly Cultural Revolution got him in the neck! The generous admiration of Soviet imperialist running dogs wasn't at all the thing to be wearing in your cap then, was it?'

Of Nelson's fall, few details are available, the Doc proclaims, speaking louder in response to Connie's outburst. 'One must assume that it was violent, and as Connie has pointed out, those who were highest in Russian favour fell the hardest.' He glances at the sheet of paper which he holds crookedly before his blotched face. 'I won't give you all his appointments at the time of his disgrace, Chief, because he lost them anyway. But there is no doubt that he did indeed have effective management of most of the shipbuilding, in Kiangnan and consequently of a large part of China's naval tonnage.'

'I see,' says Smiley quietly. Jotting, he purses his lips as if in disapproval, while his eyebrows lift very high.

'His post at Kiangnan also procured him a string of seats on the naval planning committees and in the field of communications and strategic policy. By sixty-three his name is beginning to pop up regularly in the Cousins' Peking watch reports.'

'Well done, Karla,' Guillam says quietly from his place at Smiley's side, and Smiley, still writing, actually echoes this sentiment with a 'Yes'.

'The only one, Peter dear!' Connie yells, suddenly unable to contain herself. 'The only one of all those toads to see it coming! A voice in the wilderness, wasn't he, Trot? Look out for the yellow peril, he told 'em. One day they're going to turn round and bite the hand that's feeding 'em, sure as eggs. And when that happens you'll have eight hundred million new enemies banging on your own back door. And your guns will all be pointing the wrong way. Mark my words. Told em,' she repeats, hauling at the mongrel's ear in her emotion. 'Put it all in a paper, Threat of deviation by emerging Socialist partner . Circulated every little brute in Moscow Centre's Collegium. Drafted it word for word in his clever little mind while he was doing a spot of bird in Siberia for Uncle Joe Stalin, bless him. Spy on your friends today, they're certain to be your enemies tomorrow, he told them. Oldest dictum in the trade, Karla's favourite. When he was given his job back he practically nailed it up on the door in Dzerzhinsky Square. No one paid a blind bit of notice. Not a scrap. Fell on barren ground, my dear. Five years later, he was proved right, and the Collegium didn't thank him for that either, I can tell you! He's been right a sight too often for their liking, the boobies, hasn't he, Trot! You know, don't you darling, you know what the old fool-woman's on about!' At which she lifts the dog a few inches in the air by its forepaws and lets it flop back on to her lap again.

Connie can't bear old Doc hogging the limelight, they secretly agree. She sees the logic of it, but the woman in her can't abide the reality, 'Very well, he was purged, Doc,' Smiley says quietly, restoring calm. 'Let's go back to sixty-seven, shall we?' And puts his chin back in his hand.

In the gloom, Karla's portrait peers stodgily down as di Salis resumes. 'Well, the usual grim story, one supposes, Chief,' he chants. 'The dunce's cap no doubt. Spat on in the street. Wife and children kicked and beaten up. Indoctrination camps, labour education on a scale commensurate with the crime . Urged to reconsider the peasant virtues. One report has him sent to a rural commune to test himself. And when he came crawling back to Shanghai they'd have made him start at the bottom again, driving bolts into a railway line, or whatever. As far as the Russians were concerned - if that's what we're talking about' - he hurries on before Connie can interrupt yet again - 'he was a washout. No access, no influence, no friends.'

'How long did it take him to climb back?' Smiley enquires, with a characteristic lowering of the eyelids.

'About three years ago he started to be functional again. In the long run he has what Peking needs most: brains, technical knowhow, experience. But his formal rehabilitation didn't really occur till the beginning of seventy-three.'

While di Salis goes on to describe the stages of Nelson's ritual reinstatement, Smiley quietly draws a folder to him and refers to certain other dates which for reasons as yet unexplained are suddenly acutely relevant to him.

'The payments to Drake have their beginnings in mid-seventy-two,' he murmurs. 'They rise steeply in mid-seventy-three.'

'With Nelson's access, darling,' Connie whispers after him, like a prompter from the wings. 'The more he knows, the more he tells, and the more he tells the more he gets. Karla only pays for goodies, and even then it hurts like blazes.'

By seventy-three - says di Salis - having made all the proper confessions, Nelson has been embraced into the Shanghai municipal revolutionary committee, and appointed responsible person in a naval unit of the People's Liberation Army. Six months later - 'Date?' Smiley interrupts.

'July seventy-three.'

'Then Nelson was formally rehabilitated when?'

'The process began in January seventy-three.'

'Thank you.'

Six months later, di Salis continues, Nelson is seen to be acting in an unknown capacity with the Central Committee of the Chinese Communist Party.

'Holy smoke,' says Guillam softly, and Molly Meakin gives his hand a hidden squeeze.

'And a report from the Cousins,' says di Salis, 'undated as usual but well attested, has Nelson down as an informal adviser to the Munitions and Ordnance Committee of the Ministry of Defence.'

Rather than orchestrate this revelation with his customary range of mannerisms, di Salis again contrives to keep rock still, to great effect.

'In terms of eligibility, Chief,' he goes on quietly, 'from an operational standpoint, we on the China side of your house would regard this as one of the key positions in the whole of the Chinese administration. If we could pick ourselves one slot for an agent inside the Mainland, Nelson's might well be the one.'

'Reasons?' Smiley enquires, still alternating between his jottings and the open folder before him.

'The Chinese Navy is still in the stone age. We do have a formal interest in Chinese technical intelligence, naturally, but our real priorities, like those of Moscow no doubt, are strategic and political. Beyond that, Nelson could supply us with the total capacity of all Chinese shipyards. Beyond that again, he could tell us the Chinese submarine potential, which has been frightening the daylights out of the Cousins for years. And of ourselves too, I may add, off and on.'

'So think what it's doing for Moscow,' an old burrower murmurs out of turn.

'The Chinese are supposedly developing their own version of the Russian G-2 class submarine,' di Salis explains. 'No one knows a lot about it. Have they their own design? Have they two or four tubes? Are they armed with sea-to-air missiles or sea-to-sea? What is the financial appropriation for them? There's talk of a Han class. We had word they laid one down in seventy-one. We've never had confirmation. In Dairen in sixty-four they allegedly built a G class armed with ballistic missiles, but it still hasn't been officially sighted. And so forth and so on,' says di Salis deprecatingly, for like most of the Circus he has a rooted dislike of military matters and would prefer the more artistic targets. 'For hard and fast detail on those subjects the Cousins would pay a fortune. In a couple of years Langley could spend hundreds of millions in research, overflights, satellites, listening devices and God knows what - and still not come up with an answer half as good as one photograph. So if Nelson -' He lets the sentence hang, which is somehow a lot more effective than making it finite. Connie whispers 'Well done, Doc,' but still for a while nobody else speaks. They are held back by Smiley's jotting, and his continued examination of the folder.

'Good as Haydon,' Guillam mutters. 'Better. China's the last frontier. Toughest nut in the trade.'

Smiley sits back, his calculations apparently finished.

'Ricardo made his trip a few months after Nelson's formal rehabilitation,' he says.

Nobody sees fit to question this.

'Tiu travels to Shanghai and six weeks later Ricardo -'

In the far background, Guillam hears the bark of the Cousins' telephone switched through to his room, and it is a thing he afterwards avers most strongly - whether in truth or with hindsight - that the unlovable image of Sam Collins was at this point conjured out of his subconscious memory like a djini out of a lamp, and that he wondered yet again how he could ever have been so unthinking as to let Sam Collins deliver that vital letter to Martello.

'Nelson has one more string to his bow, Chief,' di Salis continues, just as everyone is assuming he is done. 'I hesitate to offer it with any confidence, but in the circumstances I dare not omit it altogether. A barter report from the West Germans, dated a few weeks ago. According to their sources, Nelson is lately a member of what we have for want of information dubbed The Peking Tea Club, an embryonic body which we believe has been set up to coordinate the Chinese intelligence effort. He came in first as an adviser on electronic surveillance, and was then co-opted as a full member. It functions, so far as we can fathom, somewhat as our own Steering Group. But I must emphasise that this is a shot in the dark. We know absolutely nothing about the Chinese services, and nor do the Cousins.'

For once at a loss for words, Smiley stares at di Salis, opens his mouth, closes it, then pulls off his glasses and polishes them.

'And Nelson's motive?' he asks, still oblivious to the steady bark of the Cousins' bell. 'A shot in the dark, Doc? How would you see that?'

Di Salis gives an enormous shrug, so that his tallow hair bucks like a floor mop. 'Oh, anybody's guess,' he says waspishly. 'Who believes in motive these days? It would have been perfectly natural for him to respond to recruitment overtures in Leningrad, of course, provided they were made in the right way. Not a disloyal thing at all. Not doctrinally, anyway. Russia was China's big elder brother. Nelson needed merely to be told he had been chosen as one of a special vanguard of vigilantes. I see no great art to that.'

Outside the room, the green phone just goes on ringing, which is remarkable. Martello is not usually so persistent. Only Guillam and Smiley are allowed to pick it up. But Smiley has not heard it, and Guillam is damned if he will budge while di Salis is extemporising on Nelson's possible reasons for becoming Karla's mole.

'When the Cultural Revolution came, many people in Nelson's position believed that Mao had gone mad,' di Salis explains, still reluctant to theorise. 'Even some of his own generals thought so. The humiliations Nelson suffered made him conform outwardly, but inwardly, perhaps, he remained bitter - who knows? - vengeful.'

'The alimony payments to Drake started at a time when Nelson's rehabilitation was barely complete,' Smiley objects mildly. 'What is the presumption there, Doc?'

All this is just too much for Connie and once again she brims over.

'Oh George, how can you be so naive? You can find the line, dear, course you can! Those poor Chinese can't afford to hang a top technician in the cupboard half his life and not use him! Karla saw the drift, didn't he, Doc? He read the wind and went with it. He kept his poor little Nelson on a string and as soon as he started to come out of the wilderness again he had his legmen get alongside him: It's us, remember? Your friends! We don't let you down! We don't spit on you in the street! Let's get back to business! You'd play it just the same way yourself, you know you would!'

'And the money?' Smiley asks. 'The half million?'

'Stick and carrot! Blackmail implicit, rewards enormous. Nelson's hooked both ways.'

But it is di Salis, Connie's outburst notwithstanding, who has the last word: 'He's Chinese. He's pragmatic. He's Drake's brother. He can't get out of China -'

'Not yet,' says Smiley softly, glancing at the folder again.

'- and he knows very well his market value to the Russian service. You can't eat politics, you can't sleep with them, Drake liked to say, so you might as well make money out of them -'

'Against the day when you can leave China and spend it,' Smiley concludes, and - as Guillam tiptoes from the room - closes the folder and takes up his sheet of jottings. 'Drake tried to get him out once and failed, so Nelson took the Russians' money till... till what? Till Drake has better luck perhaps.'

In the background, the insistent snarling of the green telephone has finally ceased.

'Nelson is Karla's mole,' Smiley remarks at last, once more almost himself. 'He's sitting on a priceless crock of Chinese intelligence. That alone we could do with. He's acting on Karla's orders. The orders themselves are of inestimable value to us. They would show us precisely how much the Russians know about their Chinese enemy, and even what they intend toward him. We could take backbearings galore. Yes, Peter?'

In the breaking of tragic news there is no transition. One minute a concept stands; the next it lies smashed, and for those affected the world has altered irrevocably. As a cushion, however, Guillam had used official Circus stationery and the written word. By writing his message to Smiley in signal form, he hoped that the sight of it would prepare him in advance. Walking quietly to the desk, the form in his hand, he laid it on the glass sheet and waited.

'Charlie Marshall, the other pilot, by the way,' Smiley asked of the gathering, still oblivious. 'Have the Cousins run him to earth yet, Molly?'

'His story is much the same as Ricardo's,' Molly Meakin replied, glancing queerly at Guillam: Still at Smiley's side, he looked suddenly grey and middle-aged and ill. 'Like Ricardo, he flew for the Cousins in the Laos war, Mr Smiley. They were contemporaries at Langley's secret aviation school in Oklahoma. They dumped him when Laos ended and have no further word on him. Enforcement says he has ferried opium, but they say that of all of the Cousins' pilots.'

'I think you should read that,' Guillam said, pointing firmly at the message.

'Marshall must be Westerby's next step. We have to maintain the pressure,' Smiley said.

Picking up the signal form at last, Smiley held it critically to his left side, where the reading light was brightest. He read with his eyebrows raised and his lids lowered. As always, he read twice. His expression did not change, but those nearest him said the movement went out of his face.

'Thank you, Peter,' he said quietly, laying the paper down again. 'And thank you everyone else. Connie and the Doc, perhaps you'd stay behind. I trust the rest of you will get a good night's sleep.'

Among the younger sparks this hope was greeted with cheerful laughter, for it was well past midnight already.

The girl from upstairs slept, a neat brown doll along the length of one of Jerry's legs, plump and immaculate by the orange night-light of the rain-soaked Hong Kong sky. She was snoring her head off and Jerry was staring through the window thinking of Lizzie Worthington. He thought of the twin claw marks on her chin and wondered again who had put them there. He thought of Tiu, imagining him as her jailer, and he rehearsed the name horse-writer until it really annoyed him. He wondered how much more waiting there was, and whether at the end of it he might have a chance with her, which was all he asked: a chance. The girl stirred, but only to scratch her rump. From next door, Jerry heard a ritual clicking as the habitual mah-jong party washed the pieces before disturbing them.

The girl had not been unduly responsive to Jerry's courtship at first - a gush of impassioned notes, jammed through her letter box at all hours of the previous few days - but she did need to pay her gas bill. Officially, she was the property of a businessman, but recently his visits had become fewer and most recently had ceased altogether, with the result that she could afford neither the fortune-teller nor mahjong, nor the stylish clothes she had set her heart on for the day she broke into Kung Fu films. So she succumbed, but on a clear financial understanding. Her main fear was of being known to consort with the hideous kwailo and for this reason she had put on her entire out-door equipment to descend the one floor; a brown raincoat with transatlantic brass buckles on the epaulettes, plastic yellow boots and a plastic umbrella with red roses. Now this equipment lay around the parquet floor like armour after the battle, and she slept with the same noble exhaustion. So that when the phone rang her only response was a drowsy Cantonese oath.

Lifting the receiver Jerry nursed the idiotic hope it might be Lizzie, but it wasn't.

'Get your ass down here fast,' Luke promised, 'and Stubbsie will love you. Move it. I'm doing you the favour of our career.'

'Where's here?' Jerry asked.

'Downstairs, you ape.'

He rolled the girl off him but she still didn't wake.

The roads glittered with the unexpected rain and a thick halo ringed the moon. Luke drove as if they were in a jeep, in high gear with hammer changes on the corners. Fumes of whisky filled the car.

'What have you got, for Christ's sake?' Jerry demanded. 'What's going on?'

'Great meat. Now shut up.'

'I don't want meat. I'm suited.'

'You'll want this one. Man, you'll want this one.'

They were heading for the harbour tunnel. A flock of cyclists without lights lurched out of a side turning and Luke had to mount the central reservation to avoid them. Look for a damn great building site, Luke said. A patrol car overtook them, all lights flashing. Thinking he was going to be stopped, Luke lowered his window.

'We're press, you idiots,' he screamed. 'We're stars, hear me?'

Inside the patrol car as it passed they had a glimpse of a Chinese sergeant and his driver, and an august-looking European perched in the back like a judge. Ahead of them, to the right of the carriageway, the promised building site sprang into view, a cage of yellow girders and bamboo scaffolding alive with sweating coolies. Cranes, glistening in the wet, dangled over them like whips. The floodlighting came from the ground and poured wastefully into the mist.

'Look for a low place, just near,' Luke ordered, slowing down to sixty. 'White. Look for a white place.'

Jerry pointed to it, a two-storey complex of weeping stucco, neither new nor old, with a twenty-foot bamboo-stand by the entrance, and an ambulance. The ambulance stood open and the three drivers lounged in it, smoking, watching the police who mined around the forecourt as if it were a riot they were handling.

'He's giving us an hour's start over the field.'

'Who?'

'Rocker. Rocker is. Who do you think?'

'Why?'

'Because he hit me, I guess. He loves me. He loves you too. He said to bring you specially.'

'Why?'