Gribardsun assumed that this tribe had its equivalent of Simaumg, and that its doctor would be aware of the dangerousness of such a man. He was right. The witch doctor gave way completely. He lowered his baton and stared wide-eyed at Gribardsun. Then he reversed the baton and walked around the fire and handed it to him. The Englishman passed his finger through the hole in it several times and handed it back to the doctor.

Silverstein had watched all this bewildered. Gribardsun explained and then told him to put on his clothes. He doubted that anyone would interfere.

The chief and the witch doctor conferred in low tones for a while on the other side of the fire. Gribardsun got tired of waiting for them to come to a decision. He got up and put on his own clothes and resumed his place by the fire. Silverstein took out his pocket transceiver and soon got into contact with Rachel. He described as best he could their situation and location.

'We were their prisoners, and I suppose we still are,' Drummond said. 'But, somehow, John has gotten the upper hand. I don't know how long he can keep it, though.'

Silverstein confined himself to reporting the situation, though Rachel tried to get him to talk about his running away. Gribardsun gestured, and Silverstein brought the transceiver to him.

'Don't come after us,' he said to Rachel. 'You might upset the rather delicate balance of the situation. We'll keep in touch. I'll report in an hour.'

'And if you don't?' Rachel asked.

'Then you can come after us. But if this tribe loses any more men, it's going to perish.'

That evening the chief, the doctor, the big man (subdued and somewhat banged up), and a white-haired old man ate with the two prisoners in the tent. They tried to carry on a conversation with sign language. The chief managed to get across the idea that they were not prisoners but that the tribe could use the help of the two. By then the firearms had been returned to Gribardsun, who used signs to indicate that he would use his rifle to get meat for them.

Gribardsun also tried to find out from them what had happened to cause them to attack Silverstein, but he failed. Silverstein stuck to his story that they had jumped him, and he had been forced to shoot them. Gribardsun did not say anything about his narrow escape from one of Drummond's bullets. But he did not return the revolver to Drummond, nor did Drummond protest when Gribardsun dismantled the pistol and put the parts in his pack.

He did object when the Englishman said they would spend the night in the tent and perhaps stay for several days.

They'll murder us in our beds!' he said. 'They must be just waiting to catch us off guard. My God, we killed almost half their men!'

'But through what is, to them, magical means,' Gribardsun said. 'So they expect us to reimburse them somehow. We are under obligation to them. At least, that is the feeling I get. And, in a way, we are obligated.'

'But we can't support everyone we run across!' Silverstein protested. 'You've already got Dubhab's family on your hands. In fact, the whole tribe, since they've come to depend more and more on you. Would you add another tribe to your entourage?'

'We are intruders,' Gribardsun said. 'Our presence is unnatural, if anything that exists in nature can be said to be unnatural. We are here to observe and study. But our very intrusion upsets the natural order of things, so that we are not observing things as they would be if we were not here. We constitute an example of Heisenberg's Principle of Uncertainty, but in a social sense. We can't but affect what we would like to see in its natural state. So our observations are necessarily distorted or qualified.'

'I know that!' Silverstein said impatiently.

'Yes, but the point is that if we come to these people and bring catastrophe and ruin, then we must do something to help them. If we could be the ideal observers, invisible, unnoticed, then we would have an obligation not to interfere in the slightest. We could gather valid scientific data about them, and if they flourished or perished, were well or ill, tortured or the torturers, we would be the ideal observers, the unseen camera. But we can't be. To make an intimate study, we have to become intimate with them. And that, to me, involves a certain amount of obligation.'

'I don't see why we should be obligated to people who tried to kill us without reason.'

'I don't know that they had no reason,' Gribardsun said. He turned his large gray eyes on Silverstein, who flushed and chewed savagely on the piece of bison meat he had just put in his mouth.

'I feel I owe some obligations,' Gribardsun said. 'But I'm not neurotic about it. There are limits to what I owe.'

'Are you talking about them or about me?'

'Both.'

A little while later he stretched out on a pile of bison hides and apparently went to sleep almost at once. He did not cover himself with furs, as the natives did, since his thermicron suit kept him warm enough. In fact, he had to open some vents in it against getting too warm. The many bodies in the tent built up the temperature.

Silverstein opened his own suit at many places and took refuge beneath three wolf-skin blankets. But he had trouble getting to sleep. The stench of smoke and unwashed bodies and rotting teeth and chamber pots and the loud snoring of the chief and his old mother and a bite now and then from a louse kept him awake for hours. He had no sooner fallen asleep, or so it seemed to him, than a noise awakened him. He sat up and saw Gribardsun pushing the teenager blonde from him. Evidently she had just come over to him. But Gribardsun was having none of her.

In the morning, Drummond commented on the incident. Gribardsun said, 'I have no moral objection to temporary matings, and I may even have offended her deeply. She probably Wanted to have a child by me because I am a powerful magician and warrior, according to her lights. But I would feel an additional obligation if she had a child by me. I'm not ready for any such thing - yet.'

'You mean you may be ready some day?' Drummond queried. 'How could that be?'

'You'll know if it happens.'

They did not talk much during the rest of the day except on matters of business. Silverstein filmed the day's hunting, which consisted of finding a herd of bison penned inside deep walls of snow. Gribardsun shot one bull to remind the tribesmen of the power of his rifle. Then he used spears to kill several more bulls. After that, he called a halt to the slaughter. By signs he told them they shouldn't waste the meat by killing the whole herd. They wouldn't be able to haul all the meat home today, and if they left carcasses behind, the wolves would get them. The bison were trapped in the 'yard' and most of them would probably starve as soon as they had dug down through the snow and eaten all the grass under it. This was a common event; the heavy snows often trapped the herbivores.

The next day, Silverstein asked for, and got permission, to return to home camp. He hesitated for a few seconds before saying, 'I don't like to go unarmed.'

Gribardsun took the revolver and a box of ammunition from his pack. 'Use them with good sense,' he said.

Drummond flushed and said, 'Somehow, I have to clear myself. But I seem to get in deeper all the time. Yet I swear I'm innocent!'

'You haven't been proved guilty yet,' Gribardsun said. 'So you are presumed innocent until then. But that doesn't mean you're not on trial. The verdict depends on what you do in the future.'

'This is the damnedest situation!' Drummond said, striking his thigh with his fist. 'Whoever would have thought, when we got into the machine to go to 12,000 B.C., that I would be suspected of trying to murder you? Or that Rachel and I would be estranged, perhaps beyond any chance of reconciliation? This is supposed to be a scientific expedition, but if things continue as they have, we're going to fail! We'll return - if we return - with relatively little to show. And that would be a disaster! If this expedition doesn't pay off, there may never be another. Time travel costs too much!'