R. Hunter eased his muscular six and a half feet into the office chair. As usual, he looked northern European, with short blond hair and blue eyes, though he could change his shape and appearance at will. The humans on his team were all due to meet him here shortly.

Jane Maynard, the roboticist, and Steve Chang, the team’s general assistant, were having breakfast. Hunter had wanted them to have a solid night’s sleep. The team had returned only yesterday from the German rebellion against the Roman Empire in A.D. 9. During the evening, Hunter had arranged to hire an expert historian named Judy Taub for their next mission. She had arrived a short time ago and was taking a few free minutes to see the sights around Mojave Center before rejoining Hunter.

Hunter was a robot who had been especially designed and built to lead the search for Mojave Center Governor, the missing Governor robot. MC Governor, by contrast, was an experimental gestalt robot who was supposed to be running the underground desert city of Mojave Center. Instead, he had separated into his six component gestalt humaniform robots and vanished.

Each of the gestalt robots had fled back in time to a different era. Hunter and his team of humans had made three journeys in pursuit of them and had returned the first three components to the office of MC Governor, where they stood merged and shut down, waiting for the other three. However, Hunter had to report to the Governor Robot Oversight Committee on his progress after each mission. He had already requested that the city computer call the four members of the Committee for him.

“Hunter, city computer calling. I have the Governor Robot Oversight Committee on a conference call for you.”

“Please connect me.”

Split portrait shots of the four faces of the Committee members appeared on Hunter’s internal video screen. Everyone exchanged greetings. Then Hunter began his report.

“MC 3 has been joined to MC 1 and MC 2,” said Hunter.

“I can hardly believe it,” said Dr. Redfield, the tall blonde. “So fast? You’re doing a very fine job.”

“It is not complete yet, of course,” said Hunter soberly. “I cannot guarantee that the remaining searches will not take longer.”

“I understand,” said Dr. Redfield.

“Where did you locate MC 3?” Dr. Chin shook long black hair out of her face.

“In central Europe,” said Hunter. He hoped he would never have to tell them about the time travel device and so always tried to be vague in his answers to the Committee. Since he was performing his duties acceptably, they had not argued with him. “Naturally, all three gestalt robots that are in custody have been placed in a secure location.”

“You’re as efficient as usual,” said Professor Post, his smile bright in his black beard. “What information do you have about your next mission?”

“For MC 4, I have a lead in Eastern Europe at this time,” said Hunter.

“Eastern Europe?” Dr. Chin raised her eyebrows. “So close to the site of MC 3’s hiding place?”

“This is the information I have,” said Hunter carefully. “I assume it is correct.”

“You have remained on a very tight schedule,” said Dr. Khanna, a native of India. “You have retrieved one missing gestalt robot each day since you began. I look forward to seeing the completion of your duties. Personally, however, I would still like a report on your activities to date.”

“As I said before, no guarantee of consistent future results can be made,” said Hunter. He deliberately answered only Dr. Khanna’s first concern.

“Come now,” said Dr. Khanna. “Suppose we do not ask for a guarantee, but merely a prediction. Do you have any reason to believe that the next mission, for instance, will be more difficult than the previous ones?”

“I consider each mission to be a blank slate,” said Hunter. “The specific answer to your question is ‘no,’ but I have virtually no knowledge of what I shall face.”

“You’re very cautious, as always,” said Dr. Chin. “I’m sure that’s fine with us. Good luck.”

“Yes, Hunter,” said Dr. Redfield quickly. “We are not pressuring you.”

“I should begin the next mission,” said Hunter. “If you have no more questions, I shall get started.”

“Of course,” said Professor Post. “Good hunting.”

“I am not ready to sign off,” said Dr. Khanna suddenly. “I still wish to hear a report on your activities to date. Is there some reason you will not give it?”

“I am seeking the highest efficiency possible,” Hunter said carefully. Privately, that meant concealing the existence of time travel; he felt that widespread knowledge of it would harm humanity as a whole, so his adherence to the First Law would not allow him to reveal it.

“Come on, Dr. Khanna,” said Dr. Chin wearily. “We should let him get back to work. Good-bye, Hunter.”

Dr. Khanna disconnected abruptly, without speaking.

As Hunter broke his connection, Steve and Jane came into the office.

“Morning, Hunter,” said Steve cheerfully. “What’s next on the agenda?”

“Good morning,” said Jane, with a smile. Highlights in her long brown hair brightened the little room. “I guess we’re all ready.”

“Good morning,” said Hunter. He looked past Jane and saw that Judy Taub was also coming to the door of the office.

“Judy Taub, Steve Chang and Jane Maynard.”

“Pleased to meet you.” Judy was short, with curly brown hair. She shook hands with them both. “The history of the old Soviet Union is my field. The Stalin regime, including of course World War II, is my particular specialty.”

“This will be the most recent period we’ve visited,” said Jane. “Its society will be the most complex, I imagine.”

“If they didn’t have robots, our search is going to be about the same no matter what,” said Steve.

“I arranged for all three of you to have your inoculations this morning,” said Hunter. “You have taken them?”

“Yes,” said Judy.

“Of course,” said Jane.

“Yeah.” Steve nodded. “Hunter, have you briefed Judy already?”

“I have briefed her about Mojave Center Governor and the gestalt robots. Also, of course, I told her we are going back to Moscow in 1941.”

“And he swore me to secrecy,” Judy added, with an easy grin. “About the time travel. But it’s exciting. I can hardly wait to try it.”

“I have not yet explained the miniaturization of the component robots to her,” Hunter added. “Perhaps Jane can do it most efficiently.”

“Miniaturization?” Judy turned to Jane.

“I suppose the easiest way to explain the miniaturization is in terms of the Laws of Robotics,” said Jane. “The Third Law of Robotics says, ‘A robot must protect its own existence, as long as such protection does not conflict with the First or Second Laws.’ “

“Yes, I know the principle, if not the exact wording,” said Judy. “But what about this miniaturization?”

“The reasoning behind it goes like this,” said Jane. “MC Governor is the only one of the experimental Governor robots that did not shut down due to a malfunction. The Governor Robot Oversight Committee needs Hunter-and us-to restore MC Governor so they can figure out what caused the malfunction of the others.”

“Yes, Hunter told me that part.”

“But the Third Law drove MC Governor to split into his component robots and flee to avoid being dismantled during the investigation.”

“Yeah…that’s why they ran away to different times in history. Go on.”

“Well, the component robots also used the time travel process to miniaturize themselves to microscopic size,” Jane said, watching for Judy’s reaction.

“Really? I didn’t know that was possible.” Judy looked around at them all in surprise.

“Well, it wasn’t, until MC Governor developed the process himself. The component robots apparently wanted to avoid receiving any instructions from humans. Even MC 1, who went back to the dinosaur age, was anticipating that he would survive into the human era. The Second Law of Robotics says, ‘A robot must obey the orders given it by human beings, except where such orders would conflict with the First Law.’ “

“So when they became microscopic, they were invisible to humans,” Steve added. “That was the important part to the component robots.”

“And so no one would give them any orders. Okay.” Judy nodded. “Then what?”

“The process was flawed,” said Jane. “Each gestalt component robot returns to his full, normal size eventually. When he does, the Laws of Robotics will drive him to behave in certain ways-saving humans from harm, following their instructions, and saving themselves when they can-and so each robot runs the risk of changing history.”

“A very strong likelihood, in Hunter’s opinion,” Steve added with a grin.

Hunter nodded but waited patiently for Jane to finish her explanation.

“Yes, I see,” said Judy. “The First Law, in particular. I remember it now. The First Law says, ‘A robot may not injure a human being, or through inaction, allow a human being to come to harm.’ “

“Very good,” said Jane. “That’s one reason it’s so urgent for us to go back and get these robots before they change anything.”

“Only one reason? Are there more?”

“Yes,” said Hunter. “This must remain private among us, because we hope to undo this event. Have you heard on the news about the explosion in Russia?”

“I heard something on my flight here early this morning-trouble in Moscow?”

“Yes,” said Hunter. “More than ordinary trouble. A nuclear explosion has occurred.”

“A nuclear explosion?” Judy’s eyes widened suddenly. “And that has something to do with our trip back to Moscow in 1941?”

“Exactly,” said Hunter. “We have learned that when the gestalt robots return to the approximate time at which they left, an instability created by their flawed miniaturization causes them to explode with nuclear force.”

“The approximate time? Not the exact time?”

“The gestalt robots left a couple of days ago,” said Hunter. “Apparently the instability is so unpredictable that a few days’ worth of uncertainty is involved.”

“I see. Now I definitely get the picture.” She nodded gravely. “Somehow or other, you figured out that the next component robot will return to full size in 1941. So we’re going back there to get him before he can change history-and before he can explode in our own time.”

“You got it,” said Steve.

“But why did these component robots go all over the world?” Judy asked. “Why bother? Why not just go microscopic right where they were? If they expected to remain that way, what difference would it make? No human could find them anyway.”