The Watchful Eye had to proceed carefully, destroying the city by sections. Before an area could be removed, it had to make sure that no harm would come to anyone-humans, robots, the alien, the thousands of creatures in labs all over the city that still survived its genetic experiments. It merely wanted to dismantle the city and start again, so only uninhabited sectors could be destroyed.

Nevertheless, destruction was easier than creation. Many programming steps had been necessary for the design of a building, but a mere six strokes on the main computer center keyboard could remove it. The Watchful Eye scanned each structure for signs of robotic or human activity before performing the six strokes. It was still in its Bogie shape, and to a cynical observer, watching a robot attempting to destroy a city built by robots might have seemed ironic.

As soon as it had initiated its sequences of destruction, the Watchful Eye realized that the process it had to use was too well-planned, too methodical, too full of fail-safe devices. It would take a long time to demolish the entire city. If it had foreseen these complications, it would have restructured the computer’s architectural programming so that an automatic programmed sequence could be activated, one that would bypass all the fail-safe devices that the city’s clever originator had installed in the computer.

Checking the whereabouts of Derec and its other enemies, it saw that they were nearing the underground entrance. They seemed to be heading to its computer lair, no doubt to stop it from its systematic destruction of the city, and it had to stop them before it could continue.

Derec had discovered Mandelbrot and Timestep wandering the streets looking for the Bogie imposter. When they had finally worked their way through the building with the roughhousing creatures, the street outside the exit had been empty.

“It’s down at the central computer,” Derec said. “I’m sure of it. Come with me.”

The slowdown to talk with the two robots allowed Ariel and Avery to catch up. Wolruf was so far behind that the others were not even aware she was on her way.

They headed for the tunnel entrance. Just before they reached it, the frame of the entrance appeared to balloon outward and then, like an enfolding hand, cover the opening Derec had intended to pass through.

As Adam and Eve strode down a wide boulevard, they saw Wolruf lope across an intersection, then disappear down a side street.

“Let’s go after her,” Adam said. “She might know what’s happening to the city.”

Without consulting with each other, both Adam and Eve changed to the kin shape and began to pursue Wolruf, who had disappeared around a comer. When they rounded that comer, they did not see the alien ahead of them.

“She must have gone down one of those streets,” Eve said. “It will be difficult to find her.”

“I know. But these beings leave a trace in the air that we can detect through our olfactory circuits if we increase them threefold.”

Eve discovered Adam was right. There was a sweet scent of Wolruf’s fur that lingered in the center of the roadway.

Wolruf reached Derec and the others just as several buildings in a nearby block tilted, fell against each other, and collapsed, some into the street, others against buildings to the rear. The effect was as if the buildings had been made of playing cards and someone had knocked them down.

Wolruf took in the situation immediately.

“Iss there anotherr way down?” she asked.

“Lots of them,” Avery said, “but, with this creature in charge of the computer, it can block us from going in any entrance. In the meantime, it could reduce the whole city to rubble.”

There was bitterness in the doctor’s voice. No wonder, Wolruf thought, he was watching the city, his own creation, being demolished at the whim of what appeared to be a rogue robot.

“Our best bet may be to dig through this,” Derec said. “One thing our friend doesn’t know about, and that’s the potential of Mandelbrot’s arm.”

When Derec had built Mandelbrot out of spare robotic parts, he had used an arm from a Supervisor robot. It was made of an enormously malleable cellular material and could be formed into many shapes with differing densities. On many occasions it had become a most useful tool.

“Mandelbrot!” Derec said. “Do you think you could make some people-sized holes through that mess?”

He pointed toward the entrance. Although the main opening was gone, there were still some gaps where the edges of the twisted frame had not quite come together.

“Yes,” Mandelbrot replied.

“Then do it.”

“Wait,” Wolruf said. “Make a Wolrruf-sized hole firrst. I’m smallerr, and I can get down there fasster than any of ‘u.”

“No,” Derec said. “That robot isn’t like the others. It doesn’t regard you as human. Last time you went up against it, it might have killed you. It could kill you for sure this time.”

“All of ‘u take riskss. Iss my turn thiss time.”

“It’s too dangerous.”

“Don’t be such an idiot, son,” Avery said. “Pinch Me can do too much damage if we waste time getting there.”

“Pinch Me?” Ariel said. “What are you talking about? That robot down there is named Pinch Me?”

“Just a pet name,” Avery said. “Let Wolruf go down there, Derec. Wolruf, just delay him. Don’t put yourself in danger.”

“Yes,” Derec said, “just concentrate on diversionary actions, okay?”

Wolruf came from a culture where there had never been much use for diversionary action. In a conflict, her people tended to go directly for the throat. But she said, “I will be careful, I prromisse ‘u.”

Derec considered the matter for a brief time before he said, “Okay, we’ll do it your way, Wolruf.”

“Thank ‘u.”

“I’m not sure that’s proper etiquette, thanking the leader for putting you in jeopardy. Mandelbrot, start digging.”

“Yes, sir.”

Mandelbrot raised his arm, which at the moment was configured into a good copy of a human limb. As he headed toward the tunnel entrance, which looked like a jumble of the city’s strange metal, the arm began to change. First, it lengthened and an extra joint appeared at the center of the forearm. Its hand widened and fingers thinned into what looked like pointed claws. Turning its palm up to the sky, the fingers became sharp-edged at their tips. When he reached the pile, his arm was ready, and he began to rake at the twisted metal of the door frame. He managed to insert one of the fingers into a tiny opening. Making the finger thicker, he made the opening just a little bit wider.

“The metal may resist whatever abilities that arm has,” Avery said. “It’s strong.”

“So is the metal of Mandelbrot’s arm,” Derec said. “Besides, it isn’t so much a matter of tensile strength as manipulation. Wherever there’s an opening in the material the city’s made of, it can be worked with. Only a solid wall of it can stop Mandelbrot-or, for that matter, any of us. Remember, Ariel, the time I wedged a hole open with my boot?”

Mandelbrot’s hand kept changing to fulfill the needs of the task. When the hole was wider, it bec3,me a whirling wheel that knocked against the sides of the hole, widening it more. After a moment, he could reach through it. He enlarged the mass of his arm slowly and, gradually, painstakingly, he carved a hole large enough for Wolruf to get through.

“Sstop now, Mandelbrrot,” Wolruf said. “Sstand by and give me rroom. Thank ‘u.”

Without so much as a farewell, the caninoid alien entered the hole, twisting and contracting her body to propel herself through it.

When she reached the other side and began loping down the dark tunnel, Mandelbrot resumed his work on the opening.