‘I'm sorry,’ said Siever Genarr, looking down his long nose at mother and daughter with an expression that seemed to beg their pardon even without his words. ‘I had told Marlene that this job was not a very busy one and then almost immediately thereafter we had a kind of minicrisis with our power supply and I found I had to delay this conference of ours. The crisis is over, however, and wasn't much to begin with, now that we can view it in hindsight. Am I forgiven?’

‘Of course, Siever,’ said Eugenia Insigna. She was clearly restless. ‘I won't say it's been an easy three days, though. I feel that every hour we stay here increases Marlene's danger.’

Marlene said, ‘I don't fear Erythro at all, Uncle Siever.’

Insigna said, ‘And I don't think Pitt can do anything against us on Rotor. He knows that, or he wouldn't have sent us here.’

Genarr said, ‘And I will try to play the honest broker and satisfy you both. Whatever Pitt can or cannot do openly, there is a great deal he can do indirectly, so it's dangerous, Eugenia, for you to let your fear of Erythro lead you to underestimate Pitt's resolve and ingenuity. To begin with, if you return to Rotor, you will be doing so against his emergency ruling and he can imprison you or send you into exile on New Rotor or even send you back here.

‘As for Erythro, we don't dare underestimate the danger of the Plague either, even though it seems to have died out in its virulent early form. I am as reluctant to risk Marlene as you are, Eugenia.’

And Marlene whispered in exasperation, ‘There's no risk.’

Insigna said, ‘Siever, I don't think we should carry on this discussion of Marlene in her presence.’

‘You're wrong. I want to do it in her presence. I suspect that she knows better than either of us what she ought to do. She is the caretaker of that mind of hers and it is our job to interfere with her as little as possible.’

Insigna made an inarticulate sound in her throat, but Genarr went on, a quality of remorselessness entering his voice: ‘I want her in this discussion because I want her input. I want her opinion.’

Insigna said, ‘But you know her opinion. She wants to go out there, and you're saying that we must let her do what she wants to do because she is somehow magical.’

‘No-one said a word about magical, or about simply letting her go out. I would like to suggest we experiment, with all due precautions.’

‘In what way?’

‘To begin with, I would like a brain scan.’ He turned to Marlene. ‘Do you understand, Marlene, that that's necessary? Do you have any objections?’

Marlene frowned slightly. ‘I've had brain scans. Everyone has had brain scans. They don't let you start school without a brain scan. Any time you have a complete medical examination-’

‘I know,’ said Genarr gently. ‘I haven't completely wasted these last three days. I have here’ - and his hand came to rest on a stack of computer strips at the left end of his desk - ‘the computerization of every single brain scan you've ever had.’

‘But you're not telling everything, Uncle Siever,’ said Marlene calmly.

‘Ah,’ said Insigna with a touch of triumph. ‘What is he hiding, Marlene?’

‘He's a little nervous about me. He doesn't entirely believe my feeling that I'm safe. He's uncertain.’

Genarr said, ‘How can that be, Marlene? I feel quite certain about your safety.’

But Marlene said with a glow of sudden enlightenment, ‘I think that's why you waited three days, Uncle Siever. You argued yourself into being certain so that I wouldn't see your uncertainty. But it didn't work. I can still see it.’

Genarr said, ‘If that shows, Marlene, then it's only because I value you so highly that I find even the slightest risk unpleasant.’

Insigna said angrily, ‘If you find even the slightest risk unpleasant, how do you suppose I feel, as a mother? So in your uncertainty, you obtain brain scans, violating Marlene's medical privacy.’

‘I had to find out. And I did. They're insufficient.’

‘Insufficient in what way?’

‘In the early days of the Dome, when the Plague struck again and again, one of our concerns was to devise a more detailed brain scanner and a more efficiently programmed computer to interpret the data. This has never been transferred to Rotor. Pitt's exaggerated desire to hide the Plague led him to resist the sudden appearance of an improved brain scanner on Rotor. It might have given rise to inconvenient questions and rumors. Ridiculous, to my way of thinking, but in this, as in many other things, Pitt had his way. Therefore, Marlene, you have never been properly brain scanned and I want you to have one on our device.’

Marlene shrank back, ‘No.’

A look of hope crossed Insigna's face. ‘Why not, Marlene?’

‘Because when Uncle Siever said that - he was suddenly much more uncertain.’

Genarr said, ‘No, that's not-’ He stopped himself, lifted his arms, and let them drop helplessly. ‘Why do I bother? Marlene, dear, if I seemed suddenly concerned, it's because we need as detailed a brain scan as possible to serve as a standard of mental normality. Then, if you are exposed to Erythro and suffer even the slightest mental distortion as a result, it can be detected by brain scan even when no-one can tell by simply looking at you or talking to you. Well, as soon as I mention a detailed brain scan, I think of the possibility of detecting an otherwise indetectable mental change - and the thought itself sparks an automatic concern. That's what you detect. Come, Marlene, how much uncertainty do you detect? Be quantitative.’

But Marlene said, ‘Not much, but it's there. The trouble is, I can only tell you're uncertain. I can't tell why . Maybe this special brain scan is dangerous.’

‘How can it be? It has been used so - Marlene, you know Erythro won't hurt you. Don't you also know that the brain scan won't hurt you?’

‘No, I don't.’

‘Do you know that it will hurt you?’

A pause and then Marlene said reluctantly, ‘No.’

‘But how can you be sure about Erythro and not sure about the brain scan?’

‘I don't know. I just know that Erythro won't hurt me, but I don't know that the brain scan won't. Or will.’

A smile crossed Genarr's face. It did not take unusual abilities to see that he was enormously relieved.

Marlene said, ‘Why does that make you feel good, Uncle Siever?’

Genarr said, ‘Because if you were making up your intuitional feelings - out of a desire to be important, or out of general romanticism, or out of some sort of self-delusion - you would apply it to everything. But you don't. You pick and choose. Some things you know and some things you don't know. That makes me far more inclined to believe you when you claim to be sure Erythro won't hurt you and I no longer in the least fear that the brain scan will reveal anything disturbing.’

Marlene turned to her mother. ‘He's right, Mother. He feels much better and so I feel much better. It's so obvious. Can't you see it, too?’

‘It doesn't matter what I see,’ said Insigna. ‘I don't feel better.’

‘Oh, Mother,’ murmured Marlene. Then, more loudly to Genarr, ‘I'll take the scan.’

‘This is not surprising,’ murmured Siever Genarr.

He was watching the computer graphics in their intricate, almost floral patterns, as they moved slowly in and out in false color. Eugenia Insigna, at his side, stared at it keenly, but understood nothing.

‘What is not surprising, Siever?’ she asked.

‘I can't tell you properly because I don't have their jargon down pat. And if Ranay D'Aubisson, who's our local guru on this, were to explain it, neither you nor I would understand her. However, she did point this out to me-’

‘It looks like a snail shell.’

‘The color makes it stand out. It's a measure of complexity rather than a direct indication of physical form, Ranay says. This part is atypical. We don't find it in brains generally.’

Insigna's lip trembled. ‘You mean she's already affected?’

‘No, of course not. I said atypical, not abnormal. Surely I don't have to explain that to an experienced scientific observer. You'll have to admit that Marlene is different. In a way, I'm glad that the snail shell is there. If her brain were completely typical, we'd have to wonder why she seems to be what she is; where the perceptivity is coming from. Is she cleverly faking it, or are we fools?’

‘But how do you know it isn't something - something-’

‘Diseased? How can that be? We have all of the brain scans collected over her lifetime from infancy. That atypicality was always there.’

‘It was never reported to me. No-one ever remarked on it.’

‘Of course not. Those early brain scans were the usual fairly primitive type and it wouldn't show, at least not so that it would hit you in the face. But , once we have this proper brain scan and can see the detail clearly, we can go back to the early ones and make it out. Ranay has already done so. I tell you, Eugenia, this advanced brain scanning technique ought to be standard on Rotor. Pitt's suppression of it is one of his most foolish moves. It's expensive, of course.’

‘I'll pay,’ murmured Insigna.

‘Don't be silly. I'm putting this one on the Dome budget. After all, this may be helpful in solving the Plague mystery. At least, that's what I'll claim if it's ever questioned. Well, there you are. Marlene's brain is recorded in greater complexity than ever before. If she should be even slightly affected, it will show on the screen.’

‘You have no idea how frightening this is,’ said Insigna.

‘I don't blame you, you know. But she is so confident that I can't help going along with her. I'm convinced that this solid sense of security has meaning behind it.’

‘How can it?’

Genarr pointed to the snail shell. ‘You don't have that, and I don't have it, so neither of us is in a position to tell where and how she gets her sense of security. But she has it, so we must let her out on the surface.’

‘Why must we risk her? Can you possibly explain to me why we must risk her?’

‘Two reasons. First, she does seem determined, and I have the feeling that she'll get whatever she's determined to get - sooner or later. In that case, we might as well be cheerful about it and send her off, since we won't be able to stop her for very long. Secondly, it's possible we'll learn something about the Plague as a result. What that might be, I can't say, but anything, however small, that will yield additional information concerning the Plague is worth a great deal.’