`The third box?'

`The third box is the little white unit alongside the other boxes. It's a battery. We wouldn't want to be dependent on electricity in the apartment, after all. You could turn that off remotely.'

Graves had a sinking feeling, and it must have showed, because Wright laughed. `Oh, you were planning to do that, were you?' He shook his head. `Too simple. Much too simple. I wouldn't make a mistake like that.'

`What's the voltage of the batteries?' Graves snapped, trying to regain control of the situation.

`A very intelligent question,' Wright said. `I am tempted to lie, but I won't. It is a twelve-volt unit.'

`Amperage?'

`I haven't the faintest idea.'

'That doesn't concern you?'

`The amperage is adequate.'

`Adequate for what?'

Wright smiled. `Really,' he said, `you don't expect me to hand you everything on a silver platter.'

`Actually, I do.'

`Then you're being naive. How do you expect to extract information from me?' He glanced at his watch. `There is not a lot of time, and although I am sure you could torture me inventively, you couldn't get me to talk. Not fast enough.'

`Why did you close the apartment windows?'

Wright smiled. `Fascinating. I was wondering if you'd catch that. I taped them, too.'

`Yes, you did.'

`I closed the windows,' Wright said, `because the mechanism in that room anticipates some action you will take.'

`Some action I will take?'

`Yes.'

`You're being cryptic.'

`I can afford to be cryptic.'

`What's the point of the scintillation counter?'

`An interesting problem, but not so interesting as the explosives.'

Graves tried to keep his face blank, but it didn't work.

`Ah,' Wright said. `You don't know about the explosives? There was a robbery of twenty pounds of plastic explosive - Compound C, I believe it's called - earlier today, on the freeway. A hijacked truck. I'm surprised you haven't already been informed.'

Graves was beginning to sweat. He resisted the impulse to wipe his forehead. He sat back in his chair and tried to be calm.

`You seem nervous,' Wright said.

`Concerned.'

`There is no need to be nervous,' Wright said. `I can assure you right now, it is impossible for you to get into that room alive. I don't advise you to try.'

`You seem quite nonchalant.'

`Oh, I am.' He turned the cigar in his mouth, removed it, stared at the burning tip.

`We can hold you, of course.'

`You mean, prevent me from leaving San Diego?'

`Yes.'

`I'd expect that.'

`You don't care?'

`Not particularly.'

`But you'll die,' Graves said.

`A great many people will die, in fact,' Wright said, and his eyes glowed with a sudden mad intensity. `You may have noticed that weather conditions are perfect. There is an inversion layer over the city. Any released gases will be blown west - across the city -and will be trapped there. Do you know much about meteorology?'

`A little.'

`You know,' Wright said, `it's a funny thing about chemical agents. The military makes them, but they don't have much military use. By their very nature, they work best in high population density situations. And that means civilian populations. That's where you get the most bangs for your buck, so to speak.'

His eyes literally sparkled as he talked. `But the irony goes even farther,' he said. `Modern city life improves the effectiveness of these weapons. You can imagine a city like San Diego as existing with a giant plastic dome over it. That's the inversion layer. It blankets the area, holds in all the automobile fumes and exhaust gases that make city air so obnoxious.

That inversion layer will hold any released gas - or, in the case of ZV, oil droplet suspension.'

Graves snapped his fingers. `The detergent!'

`Yes,' Wright said. `Good for you. The detergent was ordered in case I had an accident in the hangar. Have to cut that oil somehow. Detergent was the best way. But,' he said, `I didn't have an accident. Nothing went wrong.'

At that moment Phelps stuck his head in the door. `Nordmann's here.'

`All right,' Graves said.

Wright looked appreciative. `Good move,' he said. `Nordmann's an excellent man. In fact, it was one of his articles - detailed, scholarly, and complete - that suggested to me the possibility of stealing some gas in the first place.'

Again there was that glow in Wright's eyes. Graves found himself getting angry. He stood up abruptly. `Don't let him go anywhere,' he said 2o the marshal.

`I wouldn't think of it, until I've finished my cigar,' Wright said.

Graves left the lobby.

Nordmann was outside, standing on the sidewalk with Phelps. They were both looking up, talking.

Graves said, `The gas is up there. Is there any antidote?'

`To ZV? Nothing very good.'

`But there is an antidote?'

`There's a sort of theoretical antidote. If a person has a mild exposure, it may be possible to inject chemicals to block the effects of the gas.'

`Can you get those chemicals?'

`Yes, but not in sufficient quantities to protect very many -'

`Get as much as you can,' Graves said. `Do it immediately.' He turned to Phelps. `Notify the San Diego

police. Evacuate this block and cordon it off. Cordon off the blocks on both sides as well. And I mean a cordon - nobody in and nobody out.' He paused. `What happened with the President?'

`He's leaving within the hour.'

`For sure?'

`I assume so.'

`Better check again.'

Phelps nodded towards the lobby. `Is he talking?'

`He's saying what he wants to say,' Graves said.

`My God, he's a cool customer.'

`What did you expect?' Graves said, and went back inside.

When he returned, he found the marshal smoking one of Wright's slim cigars. Graves shot him a look; the marshal quickly stubbed it out.

`Waste of a good cigar,' Wright said. `Why can't we all be friends?'

Graves sat down. `What did you paint in the hangar?' `Paint? amp;

'Yes. We found a spray gun and several cans of paint.'

`Oh, that.'

`What did you paint?'

`I don't believe I'll answer that.'

`What did you paint?'

`You show a certain redundancy of mind,' Wright said. `It's tiresome, and disappointing. I expected you to be more clever.' He was silent a moment. `I will tell you one thing,' he said.

`What's that?' Graves resented the eagerness that he heard in his own voice.

`I have devised a multiple staging system. Actually, several interlocking systems. If one fails or is thwarted, another takes over. It's quite beyond you, I can assure you of that. However, I will tell you I am dependent on one external system, which is fortunately quite reliable.'

`What's that?'

`You,' Wright said. `Everything has been designed especially for you, so to speak.'

Wright's calmness was infuriating. Graves bit his lip, trying to control his anger.

`What time is it?' Wright asked.

`Three forty,' the marshal said.

`Thank you. Do you have any other questions, John?'

`One or two,' Graves said. His anger was so intense that it clouded his judgement. He fought the feeling.

`I can see you're upset,' Wright said. `And you haven't asked me some rather obvious questions. One is, when will the gas go off?'

Graves stared at him, almost shaking with fury.

`The answer,' Wright said, `is five PM exactly. The gas will go off then. It will begin to drift in a predictable way and will have blanketed the city with good saturation by about five thirty, the peak of the rush hour: maximum number of people on the streets, and so on. Now, it seems to me there was something else I wanted to tell you…'

Graves wanted to beat the man to a pulp. He wanted to smash his face, to shatter his nose, his teeth… He had a brief image of himself standing over Wright, pounding him.