Insigna felt uneasy. It was Siever Genarr who had insisted that Marlene be consulted in the matter.

He said, ‘You're her mother, Eugenia, and you can't help but think of her as a little girl. It takes a while for a mother to realize she is not an absolute monarch, that her daughter is not a piece of property.’

Eugenia Insigna avoided his mild eye. She said, ‘Don't lecture me, Siever. You have no children of your own. It's easy to be pompous about other people's children.’

‘Do I sound pompous? I'm sorry. Let us say, I'm not as emotionally bound as you are to the memory of an infant. I like the girl a great deal, but I have no picture of her in my mind except that of a burgeoning young woman with a very remarkable mind. She's important , Eugenia. I have a peculiar feeling that she is much more important than either you or I. She must be consulted-’

‘She must be kept safe ,’ Insigna countered.

‘I agree, but she must be consulted as to how best to keep her safe. She is young, she is inexperienced, but she may possibly know better than we do what must be done. Let us talk among ourselves as though we were three adults. Promise me, Eugenia, that you won't try to make use of maternal authority.’

Insigna said bitterly, ‘How can I promise that? But we'll talk to her.’

So now the three were together in Genarr's office, the room shielded, and Marlene, looking quickly from one to the other, pressed her lips tightly together and said unhappily, ‘I'm not going to like this.’

Insigna said, ‘I'm afraid it is bad news. Here it is - bluntly. We're considering a return to Rotor.’

Marlene looked astonished. ‘But your important work, Mother. You can't abandon that. But I see you don't intend to. I don't understand, then.’

‘Marlene,’ Insigna spoke slowly and with emphasis. ‘We're considering that you return to Rotor. Only you .’

At that, there were a few moments of silence, while Marlene searched both of their faces. Then she said, almost in a whisper, ‘You're serious. I can't believe it. I won't return to Rotor. I don't want to. Ever . Erythro is my world. Right here is where I want to be.’

‘Marine-’ began Insigna, her voice shrill.

Genarr held up his hand in Insigna's direction, shaking his head slightly. She fell silent, and Genarr said, ‘Why are you so anxious to be here, Marlene?’

And Marlene answered flatly, ‘Because I am. You can be hungry for some particular food sometimes - just feel like eating it. You can't explain why. You just want it. I'm hungry for Erythro. I don't know why, but I want it. I don't have to explain that.’

Genarr said, ‘Let your mother tell you what we know.’

Insigna took Marlene's cold and unresponsive hand in hers and said, ‘Do you remember, Marlene, before we left for Erythro, when you were telling me about your conversation with Commissioner Pitt-’

‘Yes?’

‘You told me then that when he said we could go to Erythro, he left out something. You didn't know what that something was, but you said it was rather unpleasant - sort of evil.’

‘Yes, I remember.’

Insigna hesitated and Marlene's large penetrating eyes grew hard. She whispered, as though she was talking to herself and wasn't entirely aware that her inner thoughts were being voiced. ‘Optic flicker at head. Hand nearly at temple. Moves away.’ The sound died, though her lips continued to move.

Then, in loud outrage, she said, ‘Are you under the impression there's something wrong with my mind?’

‘No,’ said Insigna quickly. ‘Quite the reverse, dear. We know that your mind is an excellent one, and we want it to stay that way. Here's the story-’

Marlene listened to the tale of the Erythro Plague with what seemed to be the deepest suspicion, and finally said, ‘I see you believe what you are telling me, Mother, but it could be that someone told you a lie.’

‘She heard it from me,’ said Genarr, ‘and I tell you, of my personal experience, that it's all the truth. Now you tell me if I am telling the truth right now.’

Marlene clearly accepted that and moved onward. ‘Why am I in particular danger, then? Why am I in danger more than you or Mother?’

‘As your Mother said, Marlene- The Plague is thought to strike more readily at people who are more imaginative, more fanciful. There is evidence that leads some to believe that unusual minds are more susceptible to the Plague, and since yours is the most unusual I have ever encountered, it seems to me possible that you are dangerously susceptible. The Commissioner has sent instructions that you are to have a free hand on Erythro, that we're to make it possible for you to see and experience whatever you wish, that we are even to allow you to explore outside the Dome - if that is your desire. It sounds very kind of him, but might he not want to expose you to the outside in the wish, in the hope , of increasing your chance at coming down with the Plague?’

Marlene considered this with no sign of emotion.

Insigna said, ‘Don't you see, Marlene? The Commissioner doesn't want to kill you. We're not accusing him of that. He just wants to put your mind out of action. It is inconvenient to him. You can easily find out things about him and about his intentions that he doesn't want you to know, and he won't have that. He's a man of secrets.’

‘If Commissioner Pitt is trying to do me harm,’ said Marlene at length, ‘then why are you trying to send me back to him?’

Genarr raised his eyebrows. ‘We've explained it. You're in danger here.’

‘I'd be in danger there, with him. What might he do next - if he really wants to destroy me? If he thinks I'm going to be destroyed here, then he'll forget about me. He'll leave me alone, won't he? At least for as long as I'm here?’

‘But the Plague, Marlene. The Plague .’ She reached out to hug her.

Marlene evaded the embrace. ‘I'm not worried about the Plague.’

‘But we explained-’

‘It doesn't matter what you explained. I'm not in danger here. Not at all. I know my mind. I've lived with it all my life. I understand it. It's not in danger.’

Genarr said, ‘Be reasonable, Marlene. However stable you feel your mind to be, it's subject to disease and deterioration. You might get meningitis, epileptic symptoms, a brain tumor, or, eventually, senescence. Can you hold any of those things at bay just by being sure none of it will happen to you?’

‘I'm not talking about any of those things. I'm talking about the Plague. That won't happen to me.’

‘You can't possibly be sure, dear. We don't even know what the Plague is.’

‘Whatever it is, it won't happen to me.’

‘How can you tell, Marlene?’ asked Genarr.

‘I just know,’

Insigna felt her patience break. She caught Marlene by both elbows. ‘Marlene, you must do as you're told.’

‘No, Mother. You don't understand. On Rotor, I've felt a pull toward Erythro. It pulls me more strongly than ever, now that I'm on it. I want to stay on it. I'll be safe here. I don't want to go back to Rotor. I'll be less safe there.’

Genarr raised his hand, stopping whatever it was that Insigna was about to say. ‘I suggest a compromise, Marlene. Your mother is here to make certain astronomical observations. It will take her some time. Promise that, while she is busy at it, you will be content to stay inside the Dome and take such precautions as I think will make sense, and that you submit to periodic tests. If we detect no change in your mental functioning, you can wait here in the Dome till your mother is done and then we can discuss it again. Agreed?’

Marlene bent her head in thought. Then she said, ‘All right. But, Mother, don't think of pretending to be finished when you're not finished. I will know. And don't think of doing a quick job instead of a good one. I will know that, too.’

Insigna frowned and said, ‘I won't play games, Marlene, and don't think I will ever deliberately do bad science - even for your sake.’

Marlene said, ‘I'm sorry, Mother. I know that you find me irritating.’

Insigna sighed heavily. ‘I don't deny that, but irritating or not, Marlene, you are my daughter. I love you, and I want to keep you safe. As far as that goes, am I lying?’

‘No, Mother, you are not lying, but please believe me when I say I am safe. Since I've been on Erythro, I've been happy. I never was happy on Rotor.’

Genarr said, ‘And why are you happy?’

‘I don't know, Uncle Siever. But being happy is enough, even when you don't know why, isn't it?’

‘You look tired, Eugenia,’ said Genarr.

‘Not physically, Siever. Just tired inside after two months of calculations. I don't know how it was possible for astronomers in prespatial times to do what they did with nothing more than primitive computers. For that matter, Kepler worked out the laws of planetary motion with nothing more than logarithms, and had to consider himself fortunate that they had just been invented.’

‘Pardon a nonastronomer, but I thought that these days, astronomers simply gave their instruments their directions, then went to sleep and, after a few hours, woke up and found everything printed up neatly and waiting at the desk.’

‘I wish. But this job was different. Do you know how precisely I had to calculate the actual velocity of Nemesis and the Sun relative to each other, so that I could know exactly where and when the two made their closest approach? Do you know how tiny an error would be sufficient to make it seem that Nemesis would do Earth no harm when it would really destroy it - and vice versa?’

‘It would be bad enough,’ Insigna went on intensely, ‘if Nemesis and the Sun were the only two bodies in the Universe, but there are nearby stars, all of them moving. At least a dozen of them are massive enough to have a tiny effect on Nemesis or the Sun or both. Tiny, but large enough to mount up to an error of millions of kilometers one way or another, if ignored. And in order to get it right, you have to know the mass of each star with considerable precision, and its position, and its velocity.’

‘It's a fifteen-body problem, Siever, enormously complicated. Nemesis will go right through the Solar System and have a perceptible effect on several of the planets. A lot depends on the actual position of each planet in its orbit as Nemesis passes through, of course, and by how much it will shift under the influence of Nemesis' gravity, and how this shift will affect its pull on the other planets. And, by the way, the effect of Megas also has to be calculated.’