"It would leave us in a confusing position, Elijah, if the entrance were the only way of reaching Spacetown from New York City."
Baley watched his partner thoughtfully. "I don't get you. It's the only connection between the two."
"Directly between the two, yes." R. Daneel waited a moment, then said, "You do not follow me. Is that not so?"
"That is so. I don't get you at all."
"Well, if it will not offend you, I will try to explain myself. May I have a piece of paper and a writer? Thank you. Look here, partner Elijah. I will draw a big circle and label it 'New York City.' Now, tangent to it, I will draw a small circle and label it 'Spacetown.' Here, where they touch, I draw an arrowhead and label it 'Barrier.' Now do you see no other connection?"
Baley said, "Of course not. There is no other connection."
"In a way," said the robot, "I am glad to hear you say this. It is in accordance with what I have been taught about Terrestrial ways of thinking. The barrier is the only direct connection. But both the City and Spacetown are open to the countryside in all directions. It is possible for a Terrestrial to leave the City at any of numerous exits and strike out cross country to Spacetown, where no barrier will stop him."
The tip of Baley's tongue touched his upper lip and for a moment stayed there. Then he said, "Cross country?"
"Yes."
"Cross country! Alone?"
"Why not?"
"Walking?"
"Undoubtedly walking. Walking would offer the least chance of detection. The murder took place early in the working day and the trip was undoubtedly negotiated in the hours before dawn."
"Impossible! There isn't a man in the City who would do it. Leave the City? Alone?"
"Ordinarily, it would seem unlikely. Yes. We Spacers know that. It is why we guard only the entrance. Even in the Great Riot, your people attacked only at the barrier that then protected the entrance. Not one left the City."
"Well, then?"
"But now we are dealing with an unusual situation. It is not the blind attack of a mob following the line of least resistance, but the organized attempt of a small group to strike, deliberately, at the unguarded point. It explains why, as you say, a Terrestrial could enter Spacetown, walk up to his victim, kill him, and walk away. The man attacked through a complete blind spot on our part."
Baley shook his head. "It's too unlikely. Have your people done anything to check that theory?"
"Yes, we have. Your Commissioner of Police was present almost at the time of the murder - "
"I know. He told me so."
"That, Elijah, is another example of the timeliness of the murder. Your Commissioner has co-operated with Dr. Sarton in the past and he was the Earthman with whom Dr. Sarton planned to make initial arrangements concerning the infiltration of your city by R's such as myself. The appointment for that morning was to concern that. The murder, of course, stopped those plans, at least temporarily, and the fact that it happened when your own Commissioner of Police was actually within Spacetown made the entire situation more difficult and embarrassing for Earth, and for our own people, too.
"But that is not what I started to say. Your Commissioner was present. We said to him, 'The man must have come cross country.' Like you, he said, 'Impossible,' or perhaps, 'Unthinkable.' He was quite disturbed, of course, and perhaps that may have made it difficult for him to see the essential point. Nevertheless, we forced him to begin checking that possibility almost at once."
Baley thought of the Commissioner's broken glasses and, even in the middle of somber thoughts, a corner of his mouth twitched. Poor Julius! Yes, he would be disturbed. Of course, there would be no way for Enderby to have explained the situation to the lofty Spacers, who looked upon physical disability as a peculiarly disgusting attribute of the non-genetically selected Earthmen. At least, he couldn't without losing face, and face was valuable to Police Commissioner Julius Enderby. Well, Earthmen had to stick together in some respects. The robot would never find out about Enderby's nearsightedness from Baley.
R. Daneel continued, "One by one, the various exit points from the City were investigated. Do you know how many there are, Elijah?"
Baley shook his head, then hazarded, "Twenty?"
"Five hundred and two."
"What?"
"Originally, there were many more. Five hundred and two are all that remain functional. Your City represents a slow growth, Elijah. It was once open to the sky and people crossed from City to country freely."
"Of course. I know that."
"Well, when it was first enclosed, there were many exits left. Five hundred and two still remain. The rest are built over or blocked up. We are not counting, of course, the entrance points for air freight."
"Well, what of the exit points?"
"It was hopeless. They are unguarded. We could find no official who was in charge or who considered them under his jurisdiction. It seemed as though no one even knew they existed. A man could have walked out of any of them at any time and returned at will. He would never have been detected."
"Anything else? The weapon was gone, I suppose."
"Oh, yes."
"Any clues of any sort?"
"None. We have investigated the grounds surrounding Spacetown thoroughly. The robots on the truck farms were quite useless as possible witnesses. They are little more than automatic farm machinery, scarcely humanoid. And there were no humans."
"Uh-huh. What next?"
"Having failed, so far, at one end, Spacetown, we will work at the other, New York City. It will be our duty to track down all possible subversive groups, to sift all dissident organizations - "