The film ran out. The screen was white. Phelps turned the room lights back on.

`Jesus Christ,' Graves said. He lit a cigarette and noticed that his hands were shaking.

`As I said, that man received five times the minimum lethal dose,' Nordmann said quietly. `Had he got less, he would still have died - more slowly.'

`How much more slowly?'

`From tests on animals, it may take as long as an hour or two.'

`That same progression?'

`The very same.'

`Jesus Christ,' Graves said again.

He walked back into the living-room, which seemed glaringly bright. Through the windows he could look out over the downtown area of the city. He stood with his back to the television and listened to the familiar voice saying, `My fellow Americans, and my fellow Republicans, we have come to a momentous time for our nation. We face great problems, and we face great challenges. We must act now to -'

The set abruptly clicked off. Graves turned and saw that Phelps had done it. `I hope you understand now,' Phelps said. 'Wright has half a ton of that gas. In the San Diego area there are a million people. Plus some very distinguished visitors. We can't afford cat-andmouse games any longer.'

`I agree,' Graves said, staring out at the street below. There were no trees. He wondered why they hadn't put any trees in downtown San Diego. Trees made a difference.

Behind him Phelps picked up the telephone and dialled a number. He said, `Phelps here. I want 702.' There was a pause.

Nordmann came over to stand by Graves and look down at the street. `You know,' he said, `I told the Army four years ago if they kept transporting this crap all around, it was only a matter of time before somebody -'

`You have?' Phelps said into the phone. His voice was excited. `Where?'

Graves turned. Phelps was nodding, his head bobbing up and down like a mechanical bird.

`Yes, yes... yes... good work. We'll be there in five minutes.' He hung up and turned to Graves. `702 followed the limousine back to Wright's old apartment house. The van split off and went somewhere else, but the limo went back to Avenue B.'

`And?'

`They arrested John Wright as he stepped from his car.'

Graves nodded and tried to feel the same excitement that Phelps so clearly showed. But he still had a nagging sense of defeat, as if he had cheated at the game - or had quit too early.

`Come on,' Phelps said. `You can introduce him to me.'

At the apartment house two men were standing up facing the wall, guarded by the men from car 702. Phelps and Graves hurried over.

One of the men was George, the chauffeur. He was muttering something under his breath. Wright was beside him, neatly dressed in his English-cut suit.

Graves said, `You can let them turn around now.' He glanced at Phelps, who had a look of total triumph on his face.

George turned and looked at Graves uncomprehendingly. Then Wright turned, and it was Graves who stared.

`This isn't John Wright,' he said.

`What do you mean?' Phelps demanded.

`I've never seen this man before,' Graves said. `He isn't Wright. I

'We checked the wallet,' one of the 702 men said. `He has his identification -'

`I don't give a damn about identification,' Graves said. `This man isn't John Wright.'

The man in the English suit smirked slightly.

`Who the hell is he?' Phelps said.

`That,' Graves said, `is the least important question we have to answer.'

And he ran for his car.

HOUR 3
SAN DIEGO
2 PM PDT

`Take it easy,' Phelps said, grabbing the door handle. Graves took the turn from B onto Third very fast, tyres squealing. `For Christ's sake.'

`You said it yourself,' Graves said. `A million people.'

`But we have him, we know the plot, we know how it's going together -'

`We may not be able to stop it,' Graves said.

`Not stop it? What are you talking about?'

Graves raced down Third, weaving among the traffic. He ran the light at Laurel. Phelps made a gurgling noise.

'Wright has been ahead of us all along,' Graves said. `He must have switched clothes in the airfield hangar and sent somebody else back to San Diego in the limousine. He himself went with the furniture van.'

`Well, if you know where he is now -'

`I know where he is,' Graves said. `But it may be too late to stop him.'

`How can it be too late?' Phelps said.

Graves didn't answer. With a squeal of tyres he continued uptown, then turned down the wrong way on Alameda Street. Cars honked at him; he pulled over to the kerb on the wrong side, facing the wrong way, in front of afire hydrant.

Phelps didn't complain. He didn't have time. Graves was already out of the car and running for the building opposite Wright's new apartment house. In front of Wright's building was the furniture van.

All the men in the room were clustered around the cameras and binoculars at the window. Graves burst in and said, `Is Wright there?F

'I don't know,' one of the men said. `We heard he was arrested, but somebody in there sure looks like -'

`Let me see.'

Graves bent over a pair of binoculars. It took only a moment to confirm his worst fears. Wright was there, donning another rubber wet suit. He was pulling rubber loops onto his ankles, his wrists, his waist, and his neck. Of course! Those strips - six strips - protected the seams of his suit from gas. As he watched, Wright put on a full face mask and twisted the valve on the small yellow air tank. The other men in the room cleared out.

`What's he doing?' Phelps said, watching through another pair of binoculars.

Graves looked around Wright's room. The four sawhorses were still in position. Across them lay two cylinders, each about eight feet long. One was painted black, the other yellow. There were stencilled letters on their sides. As he watched, Wright began connecting hoses from each of the tanks to a central T valve, which joined the hoses into a common outlet. Then he turned his attention to other equipment in the room.

`Well, that's it.'

Phelps said, `Let's go get him.'

`You're joking,' Graves said.

`Not at all,' Phelps said. `We know he's there, we've seen him connect up the hoses so that he can -'

Phelps broke off and stared at Graves.

`Exactly,' Graves said.

`But this is terrible!V

'It's not terrible, it's just a fact,' Graves said. `There's no way we can break into that room fast enough to get control before he turns on the valves and releases the gas.'

`If we go in shooting -'

`You risk puncturing the tanks.'

`Well we can't just sit here and watch.' Phelps said.

Graves lit a cigarette. `At the moment there isn't much else we can do.'

Phelps set down his binoculars. His face was twisted; the earlier look of triumph was completely gone. `Do you have another cigarette?' he said.

Graves gave him one and then went to the phone.

'Morrison here.'

`This is Graves. We've found your tanks.'

`Listen, you better tell us -'

`They're on Alameda Street in San Diego.'

`San Diego!'

`I want you to get me some people from the Navy chemical corps. I don't care where you find them or what you do to get them, just have them here in an hour. Make sure some of them have gas-protective clothing. And make sure at least one of them knows a hell of a lot about this binary gas.'

Graves gave him the address and hung up. He glanced over at Phelps, who was sitting in a corner.

`Has somebody notified the President?'

`The President of the United States,' Graves said.

`I assume so.'

`Let's not assume,' Graves said. `Use the other phone.' And he pointed to a phone near Phelps.

Graves started to dial another call.

`I don't know how to get him,' Phelps said, in a plaintive voice.

`Use the prestige of your office,' Graves said, and turned away.

`Dr Nordmann's office.'

`This is Mr Graves from the State Department. I want to speak to Dr Nordmann.'

`Dr Nordmann had a luncheon conference and is not back yet.'

`When do you expect him?'

`Well, not for several hours. He has a faculty meeting at two thirty to discuss PhD candidates, and -'

`Find him,' Graves said, `and tell him to call me. Tell him it's about Binary 75 slash 76. Here's my number.' He gave it to the secretary.

When he hung up, one of the men at the window said, `Look what he's doing now.' Graves peered through the binoculars. He saw that Wright had removed his rubber suit and was now attaching wires to the floor of the room, to the ceiling, to the walls. He plugged the wires into a central metal box the size of a shoe box.

`What the hell is that box?' Graves said.

In a corner of the room, Phelps was saying, `Yes, that's right... That's what I'm telling you, yes... a half-ton of nerve gas... Of course it's not a joke...'

Graves saw Wright attach two small mechanical devices to the valves of the two tanks. Then he ran more wires back to the box. Finally he stacked a second metal unit on top of the original box and connected still more wires.

Then Wright looked at his watch.

`Well, somebody better get through to him,' Phelps was saying. `Yes, I'm sure it's hard...'

`What time is it?' Graves said.

`Two forty.'

`The gas is called ZV,' Phelps was saying. `An Army shipment was stolen in Utah during the early hours this morning. He's probably already been informed... Well, god damn it, I don't care if you don't know anything about it. He does... Yes, it's here...'

One of the men at the window said, `He must be insane.'

`Of course,' Graves said. `You'd have to be insane to wipe out a million people and one whole political party. But the fact is that we've really been lucky.'

`Lucky?'

`Just see that he gets the message,' Phelps said.

`Sure,' Graves said. `Those Army shipments have been going on for years. They're sitting ducks. Anybody with a little money, a little intelligence, and a screw loose somewhere could arrange for a steal. Look: Richard Speck knocked off eight nurses, but he was an incompetent. Charles Whitman was an expert rifleman, and cu that basis could knock off seventeen people. John Wright is highly intelligent and very wealthy. He's going to go for a million people and one American President. And thanks to the US Army, he has a chance of succeeding.'

`I don't see how you can blame the Army.'

`You don't?' Graves asked. He watched the other apartment through the binoculars. His eyes felt the strain; his vision blurred intermittently, and he swore. Wright appeared to be fooling with the two metal boxes in the centre of the floor. He had been adjusting them for a long time.

Graves wasn't sure what it all meant. It was a control or alarm system of some kind, though - that much was clear. And if it was a control system, it required power. Power. As Graves watched, he had an idea -one possible way to beat the system that Wright was so carefully setting up. A chance, a slim chance...

`Do it,' he whispered, watching Wright. `Do it, do

`Do what?' Phelps asked. He was off the telephone now.

Graves did not answer. Wright had finished with the boxes. He turned some dials, made some final adjustments. Then he took the main plug in his hand.

`He's going to do it,' Graves said.

And he plugged it into the wall socket. Very plainly, very clearly, he plugged it into the wall.

`He's done it.'

`Done what?' Phelps said, angry now.

`He's connected his device to the apartment electricity.'

`So?'

`That's a mistake,' Graves said. `He should have used a battery unit.'

`Because we can turn off the electricity in that apartment,' Graves said. `Remotely.'

`Oh,' Phelps said. And then he smiled. `That's good thinking.'

Graves said nothing. His mind raced forward in exhilarating high gear. For the first time all day, he felt that he was not only keeping abreast of Wright but actually moving a few steps ahead. It was a marvellous feeling.

`Time?'

`Two fifty-one.'

And then, as he watched, Wright did something very peculiar. He placed a small white box alongside the two other metal boxes. And he closed the windows to the apartment. Then he taped the joints and seams of the windows shut.

Then he left.

`What the hell does all that mean?' somebody asked.

`I don't know,' Graves said. `But I know how we can find out.'

HOUR 2
SAN DIEGO
3 PM PTD

Wright emerged from the apartment house lobby wearing a grey suit. He carried a raincoat over his shoulder. Graves was waiting for him, along with two federal marshals carrying drawn guns.

Wright did not look surprised. He smiled and said, `Did your son like his gift, Mr Graves?'

Before Graves could reply, one of the marshals had spun Wright around, saying gruffly, `Up against the wall hands wide stand still and you won't get hurt.'

`Gentlemen,' Wright said in an offended voice. He looked at Graves over his shoulder. `I don't think any of this is necessary. Mr Graves knows what he is looking for.'

`Yes, I do,' Graves said. He had already noticed the raincoat. Nobody carried a raincoat in San Diego in August. It was as out of place as a Bible in a whorehouse. `But I want to know what time it leaves.'

`There's only one possible flight today,' Wright said. `Connexions in Miami. Leaves San Diego at four thirty.'

The marshal took Wright's shoulder wallet and handed it to Graves. The ticket was inside: San Diego to Los Angeles to Miami to Montego Bay, Jamaica. The ticket was made out to Mr A. Johnson.

`May I turn around now?' Wright asked.

`Shut up,' the marshal said.

`Let him turn around,' Graves said.

Wright turned, rubbing the grit of the wall from his hands. He smiled at Graves. `Your move.' In the smile and the slight nod of the head, Graves got a chilling sense of the profound insanity of the man. The eyes gave it away.

Wright's eyes were genuinely amused: a clever chess player teasing an inferior opponent. But this wasn't chess, not really. Not with stakes like these.

Death in 1.7 minutes, Graves thought, and he had a mental image of the prisoner twisting and writhing on the floor, liquid running from his nose in a continuous stream, vomit spewing out.

Graves realized then that he had mistaken his opponent for too long. Wright was insane. He was capable of anything. It produced a churning sensation in Graves' stomach.

`Tape him inside,' Graves said to the marshal. `I want to talk to him.'

The three of them sat in the lobby of the apartment building. It was the kind of lobby that aspired to look like the grossest Miami Beach hotels; there were plastic palms in plastic pots and fake Louis XIV furniture which, apparently out of fear that someone would want to steal it, was bolted to the imitation marble floor. Under other circumstances the artificiality of the surroundings would have annoyed Graves, but now it somehow seemed appropriate. By implication the room suggested that falsehoods were acceptable, even preferable, to the truth.