That was not good. It was all exactly the way he had figured it would be, but none of it was good. He could not remember a time when he had been less pleased to be right. He turned and headed directly for the shoreline. There were many other ways in and out of the city, but this was the main entrance.

The walkway was exactly the same color as the belt of shore sand it led through. It was well camouflaged enough that it was hard to see, even from ground level. From the air it was utterly invisible. But for all of that, Caliban found it easily enough, and started to follow it as it led along the lake shore-and then down under the water itself. Ankle-deep, knee-deep, waist-deep, chest-deep, he walked out into the lake, until, at last, he was completely underwater.

People float. Robots sink. A robot could walk along the path Caliban was on, having to move somewhat more slowly underwater, but with no other real problems. A human would bob to the surface. A human wearing sufficient ballast and carrying breathing equipment could have walked that path, but not easily. But the main advantage of the under-lake entrance was that it would simply not occur to the average human that anyone would put an entrance there.

Caliban kept going, moving deeper and deeper underwater. At last he came to the complex of airlocks that made up the main entrance to the city of Valhalla. He picked the closest personnel locks, by the cargo-lock section, and cycled through, sealing the outer door behind himself, and waiting for the pumping system to pull the water out of the chamber and bleed in air from the city interior. At last the inner door opened, and Caliban stepped through.

There it was. He had expected to find it there, but he was not pleased to do so. The large personal cargo roller, in essence an airtight box that could be pulled along by the tow bar attacked to the front. The cargo roller was about the size and shape of a steel coffin on wheels-not the most happy comparison that could have sprung to mind. Caliban looked inside the steel box. Yes. There it was. An airtank with a breathing mask, and a carbon-dioxide scrubber as well. It all made sense. After all, the kidnapper could not harm his victim.

But time was short. Caliban took his blaster from its waterproof container and held in his right hand as he kept moving forward, out of the airlock complex and into the main corridors of the underground city. He thought he knew where to look for Beddle, but he could not be certain. It might be that he would have to search a fair part of the city before he found the man. He would have to work quickly.

He found the first of the murdered New Law robots just a few hundred meters from the airlocks. The body was sprawled face down on the floor of the corridor, shot through the back of the head in much the same way as the victims at the aircar site. Caliban knelt down next to the body and turned it over. It was Lancon-03, Prospero’s most recent protйgй. Lacon, it would seem, had gotten in somebody’s way.

But there was nothing Caliban could do for Lacon now-and time was short. He had to keep moving. He spotted three more murdered New Laws as he walked along. There had been nothing but a few caretakers left behind in the city to deal with last-minute details. It would seem that the kidnappers had dealt with all of them.

Each should have been mourned over, praised, remembered-but time was short. Caliban broke into a trot, hurrying forward through the sterile emptiness of the depopulated robot city. Every tidy, immaculate, sensible, utilitarian, carefully laid-out passage and street and building now was meaningless, useless. The empty town of Depot had seemed like a place that was dying, lost, abandoned. Somehow, the empty town of Valhalla seemed like a place that had never lived in the first place. Caliban thrust such thoughts from his mind and hurried on up the ramps to the upper level, the huge half-cylinder-on-its-side that was the main gallery of Valhalla. He jogged up the central boulevard and into the main administration building of the city. He slowed, and moved more cautiously up the broad, sloping ramp that led to the building’s upper story and the executive offices there.

And suddenly Caliban heard a voice. A human voice. Beddle’s voice. He tried to make out the words as he got closer. At first, he could only understand a word here and there. “-ever you want to know…promise you that-” He moved in closer, until he was right outside the door, and then he could hear it all. “I will make any promises you like, and put them in writing,” Beddle said. “Just let me out of here. You have convinced me that your cause is just. Let me leave, and-”

“If I let you leave, you will prove yourself a liar,” another voice said.

Prospero’s voice.

Caliban felt a fresh wave of revulsion wash over him. He had known it. He had been sure of it. But knowledge and proof were two different things. Up until that moment, some small part of him had prayed that he was wrong. But now that hope was gone.

He stepped into the office-Prospero’s office, his blaster at the ready. “Liar or no,” Caliban said, “you will let this human go.”

A surreal tableau greeted Caliban as he came into the room, a whole series of complex details that he took in all at once, in the space of less than a second. Prospero stood on one side of the room, in front of his desk, a magnificent panorama of the lower city visible through the view window behind him. A system of wall-mounted photosensors divided the room in two lengthwise. The sensors were attached to one long wall of the room, and spaced about twenty centimeters apart in a vertical line that went from ceiling to floor. Beam emitters lined the opposite wall, their beams aimed squarely at the photosensors, and bright enough to be plainly visible.

A complicated-looking device, roughly torpedo-shaped, but with a powerful-looking drillhead mounted on its nose, lay on the ground at Prospero’s feet. A cable led from an open hatch on the device to a junction box on the floor. Another cable led from the junction box to the photosensors.

On the opposite side of the room, behind the optical barrier formed by the photosensors, stood Simcor Beddle, leader of the Ironheads. He looked haggard and gaunt, his eyes wild with fear. He was so terrified he hardly seemed to know that anyone new had come into the room.

Beddle was a sorry sight. He was unshaven, and his hair was badly mussed. He wore a sort of shapeless gray jumpsuit that did not seem to hang on him properly, as if he had had trouble doing up the fasteners. There were sweat stains under his armpits, and a greasy sheen of sweat on his face. Simcor Beddle. Every bit of the power, the authority, the arrogance attached to his name had been swept away. He seemed numbed, in shock, scarcely aware of his surroundings. He looked toward Caliban, and yet seemed to look right through him. “Who’s there?” he demanded. “Who’s there at the door?”

Caliban ignored him, and continued his survey of the room. There was a portable refresher unit in Beddle’s side of the room, and a large supply of bottled water and survival rations stacked up on the opposite side of the room from the refresher. A primitive cot, with one blanket and one pillow, stood in the center of the cell.

And Caliban understood. The torpedo-shaped device was, of course, the burrow bomb. It was hooked up to the photosensors. If Beddle tried to step across the sensor barrier, the bomb would go up-or at least Prospero had convinced him that it would. It came to much the same thing.

But Caliban understood more than that. A robot may not injure a human being. That was the New First Law, in its entirety. And, at least by the most parsimonious and niggardly of interpretations, Prospero had not in literal fact harmed Beddle. No doubt he had carried some utterly safe anesthetic with him when he had hidden himself aboard Beddle’ s aircar. He had seen to it that the unconscious Beddle had plenty of air for his ride across the lakebed in the cargo roller. And he had provided Beddle with ample food and water, adequate sanitation facilities, serviceable clothes, and a decent bed. He had done the man no harm at all, at least in any literal, physical sense.