She had just realized that he was looking her over, and was wondering what he saw, when he put his hand on her knee. He might as well have slapped her. She was stunned.

"What are you... get your hand off me you... you groundhog."

Birkson's hand had been moving upward. He was apparently unfazed by the insult. He turned in his seat and reached for her hand. His smile was dazzling.

"I just thought that since we're stalled here with nothing else to do, we might start getting to know each other. No harm in that, is there? I just hate to waste any time, that's all."

She wrenched free of his grasp and assumed a defensive posture, feeling trapped in a nightmare. But he relented, having no interest in pursuing the matter when he had been rebuffed.

"All right. We'll wait. But I'd like to have a drink with you, or maybe dinner. After this thing's wrapped up, of course."

" 'This thing...' How can you think of something like that...?"

"At a time like this. I know. I've heard it. Bombs get me horny, is all. So okay, so I'll leave you alone." He grinned again. "But maybe you'll feel different when this is over."

For a moment she thought she was going to throw up from a combination of revulsion and fear. Fear of the bomb, not this awful man. Her stomach was twisted into a pretzel, and here he sat, thinking of sex. What was he, anyway?

The capsule lurched again, and they were on their way.

The deserted Leystrasse made a gleaming frame of stainless steel storefronts and fluorescent ceiling for the improbable pair hurrying from the tube station in the Plaza: Birkson in his anachronistic golf togs, cleats rasping on the polished rock floor, and Bach, half a meter taller than him, thin like a Lunarian. She wore the regulation uniform of the Municipal Police, which was a blue armband and cap with her rank of chief emblazoned on them, a shoulder holster, an equipment belt around her waist from which dangled the shining and lethal-looking tools of her trade, cloth slippers, and a few scraps of clothing in arbitrary places. In the benign environment of Lunar corridors, modesty had died out ages ago.

They reached the cordon which had been established around the bomb, and Bach conferred with the officer in charge. The hall was echoing with off-key music.

"What's that?" Birkson asked.

Officer Walters, the man to whom Bach had been speaking, looked Birkson over, weighing just how far he had to go in deference to this grinning weirdo. He was obviously the bomb expert Bach had referred to in an earlier call, but he was a Terran, and not a member of the force. Should he be addressed as 'sir'? He couldn't decide.

"It's the bomb. It's been singing to us for the last five minutes. Ran out of things to say, I guess."

"Interesting." Swinging the putter lazily from side to side, he walked to the barrier of painted steel crowd-control sections. He started sliding one of them to the side.

"Hold it... ah, sir," Walters said.

"Wait a minute, Birkson," Bach confirmed, running to the man and almost grabbing his sleeve. She backed away at the last moment.

"It said no one's to cross that barrier," Walters supplied to Bach's questioning glance. "Says it'll blow us all to the Farside."

"What is that damn thing, anyway?" Bach asked, plaintively.

Birkson withdrew from the barrier and took Bach aside with a tactful touch on the arm. He spoke to her with his voice just low enough for Walters to hear.

"It's a cyborged human connected to a bomb, probably a uranium device," he said. "I've seen the design. It's just like one that went off in Johannesburg three years ago. I didn't know they were still making them."

"I heard about it," Bach said, feeling cold and alone. "Then you think it's really a bomb? How do you know it's a cyborg? Couldn't it be tape recordings, or a computer?"

Birkson rolled his eyes slightly, and Bach reddened. Damn it, they were reasonable questions. And to her surprise, he could not defend his opinion logically. She wondered what she was stuck with. Was this man really the expert she took him to be, or a plaid-sweatered imposter?

"You can call it a hunch. I'm going to talk to this fellow, and I want you to roll up an industrial X-ray unit on the level below this while I'm doing it. On the level above, photographic film. You get the idea?"

"You want to take a picture of the inside of this thing. Won't that be dangerous?"

"Yeah. Are your insurance premiums paid up?"

Bach said nothing, but gave the orders. A million questions were spinning through her head, but she didn't want to make a fool of herself by asking a stupid one. Such as: how much radiation did a big industrial X-ray machine produce when beamed through a rock and steel floor? She had a feeling she wouldn't like the answer. She sighed, and decided to let Birkson have his head until she felt he couldn't handle it. He was about the only hope she had.

And he was strolling casually around the perimeter, swinging his goddamn putter behind him, whistling bad harmony with the tune coming from the bomb. What was a career police officer to do? Back him up on the harmonica?

The scanning cameras atop the bomb stopped their back and forth motion. One of them began to track Birkson. He grinned his flashiest, and waved to it. The music stopped.

"I am a fifty kiloton nuclear bomb of the uranium-235 type," it said. "You must stay behind the perimeter I have caused to be erected here. You must not disobey this order."

Birkson held up his hands, still grinning, and splayed out his fingers.

"You got me, bud. I won't bother you. I was just admiring your casing. Pretty nice job, there. It seems a shame to blow it up."

"Thank you," the bomb said, cordially. "But that is my purpose. You cannot divert me from it."

"Never entered my mind. Promise."

"Very well. You may continue to admire me, if you wish, but from a safe distance. Do not attempt to rush me. All my vital wiring is safely protected, and I have a response time of three milliseconds. I can ignite long before you can reach me, but I do not wish to do so until the allotted time has come."

Birkson whistled. "That's pretty fast, brother. Much faster than me, I'm sure. It must be nice, being able to move like that after blundering along all your life with neural speeds."

"Yes, I find it very gratifying. It was a quite unexpected benefit of becoming a bomb."

This was more like it, Bach thought. Her dislike of Birkson had not blinded her to the fact that he had been checking out his hunch. And her questions had been answered: no tape array could answer questions like that, and the machine had as much as admitted that it had been a human being at one time.

Birkson completed a circuit, back to where Bach and Walters were standing. He paused, and said in a low voice, "Check out that time."

"What time?"

"What time did you say you were going to explode?" he yelled.

"In three hours, twenty-one minutes, and eighteen seconds," the bomb supplied.

"That time," he whispered. "Get your computers to work on it. See if it's the anniversary of any political group, or the time something happened that someone might have a grudge about." He started to turn away, then thought of something. "But most important, check the birth records."

"May I ask why?"

He seemed to be dreaming, but came back to them. "I'm just feeling this character out. I've got a feeling this might be his birthday. Find out who was born at that time—it can't be too many, down to the second—and try to locate them all. The one you can't find will be our guy. I'm betting on it."

"What are you betting? And how do you know for sure it's a man?"

That look again, and again she blushed. But, damn it, she had to ask questions. Why should he make her feel defensive about it?