“Well, the point is this. Did the doctor report anything about the nature of the wound that killed Dr. Delmarre?”

“I see what you’re driving at.’ You think that perhaps the wound was too severe to have been caused by a woman.”

“A woman is weaker than a man, sir. And Mrs. Delmarre is a small woman.”

“But quite athletic, Plainclothesman. Given a weapon of the proper type, gravity and leverage would do most of the work. Even not allowing for that, a woman in frenzy can do surprising things.”

Baley shrugged. “You speak of a weapon. Where is it?”

Gruer shifted position. He held out his hand toward an empty glass and a robot entered the viewing field and filled it with a colorless fluid that might have been water.

Gruer held the filled glass momentarily, then put it down as though he had changed his mind about drinking. He said, “As is stated in the report, we have not been able to locate it.”

“I know the report says that. I want to make absolutely certain of a few things. The weapon was searched for?”

“Thoroughly.”

“By yourself?”

“By robots, but under my own viewing supervision at all times. We could locate nothing that might have been the weapon.”

“That weakens the case against Mrs. Delmarre, doesn’t it?”

“It does,” said Gruer calmly. “It is one of several things about the case we don’t understand. It is one reason why we have not acted against Mrs. Delmarre. It is one reason why I told you that the guilty party could not have committed the crime, either. Perhaps I should say that she apparently could not have committed the crime.”

“Apparently?”

“She must have disposed of the weapon someway. So far, we have lacked the ingenuity to find it.”

Baley said dourly, “Have you considered all possibilities?”

“I think so.”

“I wonder. Let’s see. A weapon has been used to crush a man’s skull and it is not found at the scene of the crime. The only alternative is that it has been carried away. It could not have been carried away by Rikaine Delmarre. He was dead. Could it have been carried away by Gladia Delmarre?”

“It must have been,” said Gruer.

“How? When the robots arrived, she was on the floor unconscious. Or she may have been feigning unconsciousness, but anyway she was there. How long a time between the murder and the arrival of the first robot?”

“That depends upon the exact time of the murder, which we don’t know,” said Gruer uneasily.

“I read the report, sir. One robot reported hearing a disturbance and a cry it identified as Dr. Delmarre’s. It was apparently the closest to the scene. The summoning signal flashed five minutes afterward. It would take the robot less than a minute to appear on the scene.” (Baley remembered his own experiences with the rapid-fire appearance of robots when summoned.) “In five minutes, even ten, how far could Mrs. Delmarre have carried a weapon and returned in time to assume unconsciousness?”

“She might have destroyed it in a disposer unit.”

“The disposer unit was investigated, according to the report, and the residual gamma-ray activity, was quite low. Nothing sizable had been destroyed in it for twenty-four hours.”

“I know that,” said Gruer. “I simply present it as an example of what might have been done.”

“True,” said Baley, “but there may be a very simple explanation. I suppose the robots belonging to the Delmarre household have been checked and all were accounted for.”

“Oh yes.”

“And all in reasonable working order?”

“Yes.”

“Could any of those have carried away the weapon, perhaps without being aware of what it was?”

“Not one of them had removed anything from the scene of the crime. Or touched anything, for that matter.”

“That’s not so. They certainly removed the body and prepared it for cremation.”

“Well, yes, of course, but that scarcely counts. You would expect them to do that.”

“Jehoshaphat!” muttered Baley. He had to struggle to keep calm.

He said, “Now suppose someone else had been on the scene.”

“Impossible,” said Gruer. “How could someone invade Dr. Delmarre’s personal presence?

“Suppose!” cried Baley. “Now there was never any thought in the

robots’ minds that an intruder might have been present. I don’t suppose any of them made an immediate search of the grounds about the house. It wasn’t mentioned in the report.”

“There was no search till we looked for the weapon, but that was a considerable time afterward.”

“Nor any search for signs of a ground-car or an air vehicle on the grounds?”

“No.”

“Then if someone had nerved himself to invade Dr. Delmarre’s personal presence, as you put it, he could have killed him and then walked away leisurely. No one would have stopped him or even seen him. Afterward, he could rely on everyone being sure no one could have been there.”

“And no one could,” said Gruer positively.

Baley said, “One more thing. Just one more. There was a robot involved. A robot was at the scene.”

Daneel interposed for the first time. “The robot was not at the scene. Had it been there, the crime would not have been committed.”

Baley turned his head sharply. And Cruer, ,who had lifted his glass a second time as though about to drink, put it down again to stare at Daneel.

“Is that not so?” asked Daneel.

“Quite so,” said Gruer. “A robot would have stopped one person from harming another. First Law.”

“All right,” said Baley. “Granted. But it must have been close. It was on the scene when the other robots arrived. Say it was in the next room. The murderer is advancing on Delmarre and Delmarre cries out, ‘You’re going to kill me.’ The robots of the household did not hear those words; at most they heard a cry, so, unsummoned, they did not come. But this particular robot heard the words and First Law made it come unsummoned. It was too late. Probably, it actually saw the murder committed.”

“It must have seen the last stages of the murder,” agreed Gruer. “That is what disordered it. Witnessing harm to a human without having prevented it is a violation of the First Law and, depending upon circumstances, more or less damage to the positronic brain is induced. In this case, it was a great deal of damage.”

Gruer stared at his fingertips as he turned the glass of liquid to and fro, to and fro.

Baley said, “Then the robot was a witness. Was it questioned?”

“What use? He was disordered. It could only say ‘You’re going to kill me.’ I agree with your reconstruction that far. They were probably Delmarre’s last words burned into the robot’s consciousness when everything else was destroyed.”

“But I’m told Solaria specializes in robots. Was there no way in which the robot could be repaired? No way in which its circuits could be patched?”

“None,” said Gruer sharply.

“And where is the robot, now?”

“Scrapped,” said Gruer.

Baley raised his eyebrows. “This is a rather peculiar case. No motive, no means, no witnesses, no evidence. Where there was some evidence to begin with, it was destroyed. You have only one suspect and everyone seems convinced of her guilt; at least, everyone is certain no one else can be guilty.’ That’s your opinion, too, obviously. The question then is: Why was I sent for?”

Gruer frowned. “You seem upset, Mr. Baley.” He turned abruptly to Daneel. “Mr. Olivaw.”

“Yes, Agent Gruer.”

“Won’t you please go through the dwelling and make sure all windows are closed and blanked out? Plainclothesman Baley may be feeling the effects of open space.”

The statement astonished Baley. It was his impulse to deny Gruer’s assumption and order Daneel to keep his place when, on the brink, he caught something of panic in Gruer’s voice, something of glittering appeal in his eyes.

He sat back and let Daneel leave the room.

It was as though a mask had dropped from Gruer’s face, leaving it naked and afraid. Gruer said, “That was easier than I had thought. I’d planned so many ways of getting you alone. I never thought the Auroran would leave at a simple request, and yet I could think of nothing else to do.”