'Fair enough.'

They were still standing there when I came back. The silence was almost total now and I could hear the rustle of a sleeve as someone in the control room moved his arm. Nobody looked at me, but I was the only man among the whole of the complement they were thinking about. As soon as they could spit this bloody frog out of the escape hatch they could start engines and get the hell out of here before some yellow bastard spotted them.

'Skipper,' I said, 'I'd like to take a final look.'

'By all means.'

He led me into the control room.

I knew they wanted me out of Swordfish as fast as possible but I couldn't help that. I had to establish the image of the rig and I had to do it now and from this precise position because later it wouldn't be stable and I could lose my bearings. We were to the north-east of the thing and midway between it and the San-Men Islands and I wanted to memorize the rig's configuration from this exact angle because if a sea haze covered the Pole Star and the rig's structure sent my compass wild I'd have nothing left but this image as my guide.

'Up 'scope.'

Ackroyd stood aside and I took the grips, turning the sights until the cross-hairs swung to centre on the rig. At this distance it reached twenty or so degrees from the horizontal and I could see its riding lights. There was some kind of flood illumination hitting the cranes and derrick from lamps on the top deck, and a flare pilot was burning with a steady flame from the tip of a stackpipe.

At one side I could make out the black aerodynamic shape of a helicopter, the object we most feared, 'Thank you.'

'Our pleasure.'

The 'scope was brought down and I went through to the wardroom. A young seaman was coming the other way and stood aside for me, his leg catching one of my reserve air tanks: it hit the metal bulkhead and someone said shit under his breath and the seaman's face went white. We all stood perfectly still for a minute, trying to replay the sound in our memory to judge how bad it was.

It wasn't very good so I did a final synchronization check with Ferris and tugged the flippers on and carried the reserve tanks and other stuff along to the escape hatch. Ackroyd led the way personally, which I thought was civil of him.

Ferris helped me stow the gear against the bulkhead and I checked the faceplate for misting.

'Better you than me,' Ackroyd murmured. He had a very held-in smile.

'I wouldn't want your job either,' I said and put the mask on. They swung the door shut without making a noise and the last thing I saw was the pale and watchful face of Ferris, not much of his mind on me, most of it going through a lightning series of checks to see if we'd forgotten anything, overlooked anything, anything that could catch up on us a minute from now or an hour from now or at noon today when I was alone in the target zone and out of reach.

Flooding began.

The sickly rubber smell of the mask.

I shifted the lead belt around an inch, unnecessarily.

The water was waist high.

The thing I had to do was simple. Difficult but simple. During final briefing I'd asked Ferris why the hell didn't we take up station at the Golden Sands Hotel and do a snatch on Tewson the next time he was brought ashore to see his wife? There were three reasons, he'd said. One: Tewson might never go there again. Two: London wanted the evidence. Three: London wanted to know what the evidence was.

The water touched my chin. The mask had started to mist up so I pulled it off and spat into the faceplate and wiped it clear and put it back.

If Tewson never went to the hotel again we could lose him forever: he could disappear into mainland China and that would be that. Presumably the evidence London wanted was to be used against Tewson or through diplomatic channels against Pekin or maybe both. And the evidence London wanted was the evidence of what Tewson was doing on board the rig.

Water above my head. Vision distorted, sound magnified as the water gushed in from the pipes. Left hand stinging: salt in the wound.

Ferris would tell London straight away: he'd have to, because Egerton always insisted on phase situation reports going in on time and it was no good telling him later that you were up a steeple or down a drain. The moment this watertight hatch opened Ferris would have to say so, either through Admiralty Signals and Crowborough or ship-to-shore cable to Chiang in cypher, the standing contraction: Access phase open, executive in target zone.

The hollow ringing sound of the water died away and there was just the steady inspiration and expiration of my lungs, with the soft cathedral echoes. Then hinges turned and a circle of pale light appeared above me and I pushed gently upwards, floating away.

The sea was dead calm and the light milky, with the waning moon trailing a pale gold disc above me on the surface. Minutes later I thought I heard the pulsing of the sub's engines but I wasn't sure: the senses were having to adjust to the laws of this other world where the ears must listen under pressure and the eyes see things as larger than they were, and closer. Halfway to the rig I turned and floated on my back, sighting along the surface through the faceplate. The island was there on the near horizon: Heng-kang Chou. I'd been moving off-course, and when I turned again I saw the rig's configuration had altered noticeably. This worried me because there'd been no figures we could hope to work out for the target-zone duration: I could hold out for three days in terms of rations and drinking-water but that didn't have any reference to the amount of time I'd spend submerged. Standard practice was to economize with the air supply and leave a ten per cent margin of error in making calculations, and you don't economize with the air supply by going off-course.

Watch what you're bloody well doing.

I'd been using the compass because they had radar and there'd be look-outs on the rig. The phosphorescent dial was clear enough to read accurately but the steel substructure was beginning to send the needle wild and from now on I'd have to risk it and take direct visual checks at intervals with the faceplate clear of the surface till I could pick up the base of the rig below water. I was moving almost due south and the moon was climbing in the east and I'd have to avoid tilting my head to the left when I surfaced the faceplate, to minimize reflection from the glass.

They didn't have sonar. We'd known that, long before we'd reached our position. If they'd had sonar they would have sent the chopper aloft to investigate our sound and we'd have seen it and Ackroyd would have turned about or surfaced, signalling difficulties. The main danger would have come from divers below the rig: if the substructure was under repair or there were modifications being made they'd have divers down and they would have picked up the sound of our screws.

I submerged again, moving a few feet below the surface, low enough to prevent the kick of the fins from making a disturbance, high enough to preserve buoyancy. I began looking for the outlines of the substructure ahead of me now but the water was cloudy in patches: it could be just plankton or weed debris, or the machinery on board the rig was perpetually disturbing the sea bed. I began worrying about exhalation bubbles but there wasn't anything I could do: they'd still break the surface from whatever depth I went down to. Ignore.

The world was silent around me, my own sound alone disturbing it: the hollow and echoing rhythm of my breathing as the living bellows of my lungs fed on the inert reservoirs of air and blew it out, each breath exhausting it by degrees, and irrecoverably. Sometimes the reserve tanks and the other gear caught an eddy from my fins and pulled me sideways a little, dragging on the nylon cord, and every time this happened I rose and broke the surface with the faceplate to correct my course: but I didn't like having to do it because this whole operation was so bloody sensitive.