Martin moved closer to the door. `I think so -'

`Maybe you shouldn't -'

Martin began to cough. His nose ran. `Shit,' he said. `What is this?' He coughed again.

Jencks went forward to help him. Then Jencks felt the stinging in his nostrils, and the liquid began to pour over his shirt. He didn't know a nose could run that way. His eyes ached and stung; he felt dizzy. `What the hell…' He had a coughing fit.

The walkie-talkie crackled. `This is Phelps,' a voice said. `Over.'

Martin took a step towards the walkie-talkie and fell to the floor. Now he could see the faint wispy whiteness seeping through the door.

`This is Phelps. Over.'

Jencks was coughing loudly and groaning.

Martin stretched out his hand towards the walkietalkie. He was weak. His arm trembled. Then, without warning, he vomited and lost consciousness.

`I'm not getting an answer,' Phelps said.

Graves and Nordmann exchanged glances, then looked back out the window at the opposite apartment. The room now had a faint milky haze.

`Are they dead?' Phelps said.

`Probably.'

`How can you just stand there?F

'Because,' Graves said, `it was just a short burst. The valves are turned off again.'

Phelps looked puzzled.

`It wasn't a full release,' Graves said. `It's just a partial release, to fill the room with gas. That's why Wright carefully closed the windows. Now we really can't get in there.'

`You sound so appreciative,' Phelps said.

`I'm not. But we understand now what Wright meant by a complex staging sequence.'

`God damn it, this is not a jigsaw puzzle! Two cops have died and -'

`We're all right,' Nordmann said quietly, `until five PM.,

'And what do you intend to do between now and then?' Phelps demanded angrily. `I'm going to call the Navy,' he said. `Their men were supposed to be here an hour ago. It's four thirty now.'

Graves stared at the gas-filled apartment. He had a brief mental image of the two cops staggering drunkenly in the hallway. He pushed it away; he could consider it later.

Beside him Nordmann said, `It's really quite clever.'

Graves said, `How thick is the gas in that room?'

`Hard to say,' Nordmann said. `The normal colour of the gas is white. I don't think the density is very great. Why?'

`If you shot me full of those antidotes, could I survive the atmosphere in that room?'

`I don't know.'

`Would I have a chance?'

`A chance? Of course. But even if you could survive, how would you get in? You said yourself it's wired with explosives. You can't go in the front door.'

`I wasn't thinking of the door,' Graves said. `I was thinking of the window.'

`The window?' Nordmann frowned. `I don't know

..Graves looked down at the street below, where an ambulance had pulled alongside the wrecked Alfa. A half-dozen cops and orderlies were trying to open the door, but it was still jammed shut. `Damn,' he said. `I wish he were still alive.'

`It probably wouldn't matter,' Nordmann said absently. He was staring across at the other building.

Graves said, `How good are my chances with the antidote?'

`Four thirty-five,' somebody said.

`Maybe one in two,' Nordmann said. `At best.'

`All right. Let's do it.'

`Are you sure?'

'What choice do I have?'

Nordmann considered this, then nodded. `Sit down,' he said. `I'll fix a syringe.'

He quickly filled a syringe with two solutions, one pale yellow, the other clear.

Graves sat and watched him. `How do I take it?'

`Intravenously.'

`You mean, in the vein?'

`Yes.'

`I can't possibly shoot into my veins.'

`You can,' Nordmann said, `if I tape on an IV line. Roll up your sleeve.'

Graves rolled up his sleeve, and Nordmann tied a rubber tourniquet around his arm. He slapped the veins to make them stand out. Then he turned back to the syringe. `I hope I've got this mixture right,' he said. He tapped the bubbles of air out of the syringe.

`So do I,' Graves said.

Nordmann attached the syringe to a piece of flexible plastic tubing. At the end of the tubing was a needle. `I'll put the needle into your vein,' he said, `and tape the syringe to your arm. Just before you enter the room, you can inject the contents.'

Graves felt the coldness of alcohol on his forearm, and then the prick of the. needle.

`Don't move,' Nordmann said. `Let me tape it down.' He removed the tourniquet, applied the tape, and stepped back. `Done.'

Graves looked at the equipment taped to his arm. `You sure this will work?'

`I told you the odds,' Nordmann said.

Graves stood up. `Okay,' he said. `Time?'

`Four thirty-nine.'

`Let's go,' he said, and ran for the elevator.

They came to the street and ran outside. By his side Nordmann was puffing, red in the face. Graves felt no strain at all; he was tense and full of energy. `Rope,' he shouted to a cop. `We need rope.'

The cop went off to get some.

`Hurry!'

The cop hurried.

Graves looked at Nordmann. `Listen,' he said. `I just had a thought. The gas leaked out of the nineteenth floor and killed those two cops. Right?'

`Right.'

`What's to prevent us from getting knocked off in the elevator as we go up to the twentieth floor?'

`Nothing,' Nordmann said. `It's a risk we have to take. If enough gas has leaked back into the building, we may die on our way up.'

`Is that all you have to say?'

Nordmann shrugged. `That's the situation.'

Two burly cops came over. One had a coil of white nylon rope over his shoulder. `Come with us,' Graves said. And he ran with Nordmann into the apartment building.

The elevator creaked up slowly. Graves fidgeted. Nordmann seemed very calm. The two cops looked at each other, obviously not understanding what was going on. They stared suspiciously at the syringe taped to Graves' arm.

They passed the tenth floor.

`Listen,' Graves said. `I had another thought. ZV is an oil, right?'

`Yes.'

`Well, when I get into that room, all the surfaces will be coated with oil. And deadly. Right?'

`Probably not,' Nordmann said. `It takes time for the droplets to settle. If the room is cleared of gas fast enough, the surfaces should be safe.'

`You sure?'

`I'm not sure about anything.'

They passed the fifteenth floor. Graves resisted the impulse to hold his breath. He looked at Nordmann. Nordmann crossed his fingers.

Seventeenth floor. Eighteenth floor. Nineteenth floor. Graves waited for the gas to hit him, but nothing happened. They came to the twentieth, and the doors opened.

`We made it,' he said.

`So far,' Nordmann said.

They hurried down the corridor.

`Time?'

`Four forty-two,' one of the cops said.

They came to Apartment 2011, the one directly above Wright's. The building had been evacuated and the door was locked. The two policemen threw themselves at the door. It didn't move. They tried again without success.

Nordmann went hurrying down the hallway and returned with a fire axe. He swung once at the door. The axe barely bit into the wood.

`Let me do that,' one of the cops said, and swung hard near the lock.

`Knock it down, knock it down,' Graves said.

It took time. There was no easy crash and splintering; the wood was new and strong and thick. Finally the cop managed to bash a hole large enough to admit his hand. He reached in and turned the lock. The door swung open, and they came into an apartment that was all chintz and doilies and heavy furniture.

Graves went directly to the window and flung it open. He looked out and down, feeling the hot, gusty August wind. He was sweating hard.

One of the cops tied the nylon rope around his waist.

`Tell me what I do,' Graves said to Nordmann, and pointed to the syringe.

`Okay,' Nordmann said. `You press that syringe to give yourself an injection of the antidote. You can push the plunger this far -' he touched the side of the syringe `- and be safe. More than that, and you will suffer effects similar to the gas itself. Clear?'