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.

`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.