However, even as she was considering this possibility, Mme Salminen's head was flung back against the chair, suddenly and violently, so that she was staring up at the ceiling, her hair flowing loose, her mouth slack and open. Then Mr Dunn was hurled backwards bodily from the table and flattened against the wall, his feet several inches off the ground. The next instant the single candle was extinguished and the room was suddenly plunged into an impenetrable velvety darkness. The heavy table was upended with a violent crash, and Mr Dunn fell to the floor, screaming in what appeared to be Hindustani: 'Save me… from her… pursuit… beg mercy… '

The strangest aspect of these hallucinations, the Countess records, was that even in that darkness which was not merely the absence of light but rather its opposite, an antithesis that could only be conceived in the inner eye of the mind: even in this blank darkness they could see C. C. Dunn absolutely clearly, although not with the kind of vision that depends on light; they could see him struggling; the agonies that passed over his face; they watched his futile attempts to fight off whatever it was that had tied him upon this rack of torment – all this they could see, but never once did they glimpse or even imagine the agent of his anguish, what arm or instrument, or whatever means it was through which these hideous agonies were effected. His face was livid with fear, and they saw him flailing his arms, fighting something off, a hand, or possibly an instrument. They saw him cowering on the floor, prostrate but not unconscious, but then just as suddenly the nature of his struggle changed, and he seemed instead to be grappling with an animal, fighting to keep its fangs from closing around his throat; shouting a repetitive string of invocations.

Then abruptly the noise ceased and the candle flared up again so that they were no longer in darkness. Opening their eyes they saw that the table was exactly where it had been, and that they were all sitting in their places, except the unannounced guest, who was cowering in a corner, stark naked.

And then Mme Salminen spoke her first words, in a whisper so soft as to be audible to none other than the countess, who was seated beside her. All this while Mme Salminen had been sprawled in her chair, her head thrown back, her eyes blank and unseeing. When she spoke it was without properly regaining consciousness. The sentence that escaped her lips was: 'There is nothing I can do: the Silence has come to claim him.'

Having said these few words she collapsed on the table.

Her alarmed acolytes removed her immediately to her bedroom, where she remained until well into the next day. On gaining consciousness her first act was to send for the countess. The two women remained closeted together for several hours.

Unfortunately the Countess never provided a written account of their conversation of that day, but she is known to have described it later as the turning point of her life.

However the actual influence of Mme Salminen on her disciple's subsequent career remains disputed. For instance, when she attributed her pioneering archaeological work in excavating early Manichaean and Nestorian sites in Central Asia, Nepal and Bengal to the influence of Mme Salminen, her friends assumed that this was merely a manner of speaking – a grateful acolyte's rendering of homage. But in her advocacy of the teachings of Valentinus, the Alexandrian philosopher of the early Christian era, they were more inclined to take her assertions at face value. When she asserted that it was Mme Salminen who had revealed to her the truth of the Valentinian cosmology, in which the ultimate deities are the Abyss and the Silence, the one being male and the other female, the one representing mind and the other truth, few disputed her account of the matter, for these beliefs clearly did not merit a prosaic explanation.

Yet, accustomed as her friends were to her eccentricities, they became seriously concerned when she moved to Egypt in the late 1940s, to search for the most sacred site of the ancient Valentinian cult: the lost shrine of Silence. Some of them were to recall later, after her disappearance, that she had often spoken of a description that Mme Salminen had given her: of a small hamlet on the edge of the desert; of date palms and mud huts and creaking waterwheels.

Chapter 32

URMILA SHIVERED, despite the clammy heat.

'So do you think it's all connected?' she said. 'The message that was sent to you, and these bits of paper that the fish were wrapped in… '

'Are you kidding?' Murugan said. 'You bet they're connected. Your fish wrappings pull it all together. Look at it this way: Cunningham had the only lab on the continent where Ron had a snowflake's chance of making a breakthrough; Ron knew this and by late 1896 he was desperate to get his ass to Calcutta. But Cunningham just wasn't buying it: he'd set this lab up like his own backyard barbecue and he wasn't going to let some punk kid break up his party. Ergo: if Cunningham was the principal obstacle to Ron's moving to Calcutta, it follows that at this point in time – late 1897 – he was the single greatest obstacle to the solution of the malaria puzzle. If someone was looking over Ron's shoulder at this stage, it wouldn't take them long to figure this out. So what do they do? They call a timeout and go into a huddle and when they go back on the floor they've got a new gameplan: Cunningham's got to go. And sure enough, that's exactly what happens: suddenly in January 1898, Cunningham changes his mind; he throws the game and takes his tail off to England. In between he makes a pit-stop in Madras where he goes through some kind of psychotic episode. Those papers, that message on my screen – someone is trying to get me to make connections: they want me to know I was on the right track'

'But wait a minute,' said Urmila. 'What do you mean "want you to know"? It wasn't you who found the papers. It was me – and I met you by accident – because you happened to be at Romen Haldar's house when I… when I fainted.'

'Is that right?' said Murugan. 'OK, now you tell me exactly how you happened to "find" those papers and we'll try and see if your accident theory holds up.'

Urmila began to tell him about the events of that morning, and the night before – the phone-call to her family, her promise to cook fish, and the providential ring of the doorbell at seven fifteen. And slowly, as she told the story, her account grew more and more uncertain, so that when she got to the unknown fish-seller, her voice faded into a barely audible murmur.

'But why would anyone set about the whole thing in such a roundabout way?' she said. 'If they want you to know something why wouldn't they just tell you – why involve me and Romen Haldar and…?'

Murugan paused to scratch his beard. 'The truth is,' he said, 'that I don't know. But a couple of things are clear enough. Someone's trying to get us to make some connections; they're trying to tell us something; something they don't want to put together themselves, so that when we get to the end we'll have a whole new story.'

'Why?' said Urmila. 'What purpose does it serve? What good will it do them if we get to the end or not?'

'I'm not absolutely sure,' said Murugan, 'but I guess I could sketch one possible scenario.'

'Go on,' said Urmila.

'All right,' said Murugan. 'Now suppose, just suppose you had this belief – don't ask me why or anything, this is strictly a let's pretend game – just suppose you believed that to know something is to change it, it would follow, wouldn't it, that to make something known would be one way of effecting a change? Or creating a mutation, if you like.'

Urmila made a doubtful noise.

'Now let's take this one step further. If you did believe this, it would follow that if you wanted to create a specific kind of change, or mutation, one of the ways in which you could get there is by allowing certain things to be known. You'd have to be very careful in how you did it, because the experiment wouldn't work until it led to a genuine discovery of some kind. It wouldn't work, for instance, if you picked someone out of a crowd and said: "Yo, here's a two and here's another; add them up and what do you get?" That wouldn't be a real discovery because the answer would be known already. So what you would have to do is to push your guinea pigs in the right direction and wait for them to get there on their own.'