I wasn't thinking about the London directive Ferris had thrown me because there wasn't any point.

I would have said no straight away and shut the set down on that but Egerton always likes you to give it a bit of thought before you tell him he's run the mission into the ground. It wasn't that he didn't realize what he was asking me to do: when the executive's in the target zone the director in the field is normally in rapid and constant signals with Control. The moment I'd left Swordfish they'd lit up the red bulb over the mission board for Mandarin in London and it wouldn't go out till I'd left the target zone or blown the operation or got snatched or neutralized by the opposition.

Ferris had had all the time he needed to tell Egerton precisely what the situation was and Egerton therefore knew bloody well that I didn't stand a hope in hell of bringing Tewson off this rig. I'd set up a get-out action when I'd gone aboard but London didn't know that and in any case it was in the extreme resource category and I put my chances at ten to one against getting away with it. This was nothing but routine procedure: when you go into the target zone you leave every possible door wide open behind you and if there's anything you can use for a last-minute hit-and-run get-out you give it a go because in a lot of cases the alternative's a ten-year stretch in a brainwash facility or a six-foot hole where no one can see them digging.

I'd made no provision for pulling a man out with me and there wouldn't have been anything I could have done about it even if London had briefed me on it before we'd gone into the access phase: the rig was manned and guarded and Tewson was under the protection of the opposition and it was no go all along the line.

Ferris knew that. He'd been instructed to field-brief me with the signal and he'd done that. I'd received the directive and acknowledged it and all I could do now was hole up on Heng-kang till tonight and come back and go over the rig again to see if I could fill in a few of the gaps: try finding out what type of missile they were going to plug into this thing, take a closer peek at the unit that looked like a tropospheric scatter system, do a soft-shoe snatch on one of the guards and get him into cover and see if he Could understand Cantonese.

But that would be all I could do before I had to pull out and when I pulled out I couldn't bring Tewson with me. They bloody well ought to know that.

Even at this depth I could feel the vibration of the riveter in the pontoon leg and when I lashed the used air tanks to the girder they began ringing to the percussion: at four atmospheres the residue of air was being compressed by seventy-five per cent and the vibration was hitting them like a drum, so I took them off and looped some of the cord round the girder to damp out the metal-to-metal contact before I lashed everything tight and damn nearly knocked into him when I turned round because he was right behind me and reaching for his knife.

High cheekbones and light yellow eyes behind the mask, nothing on him except the diver's knife, no spear-gun or anything. His move for the knife surprised me because you can't use any kind of blade under water with enough speed to do any damage: you've got to wait till you can get in close and then start ramming with it. He was shorter than I was and that meant he couldn't get in close unless I let him and I wasn't going to do that and he ought to know.

Conceivably it was just a defensive reaction when I'd turned round: he was offering the knife correctly, hilt down and blade up at forty-five degrees — he knew how to use the thing and unless I backed off it wouldn't be any good reaching for my own knife because he'd be ripping into me before I could get anywhere near it.

We looked at each other through our faceplates for two or three seconds before we made a move. Everything was in the eyes: not communication but reaction. His eyes were alert and hostile, the lids narrowed and the pupils enlarged. He watched me with total attention. In my own eyes he'd seen shock and now saw decision. Man is- one of the territorial animals and contact between two members of their species gives rise to an immediate issue when one or the other is on his own ground. For both of them — but particularly for the intruder — there is the primitive decision to be made: to fight or run.

But he hadn't been waiting to see what I would do. The situation was more sophisticated than it would have been for two of the lower animals: this diver had seen me lashing something to the base of the rig and it could be explosive and whatever it was he wanted to find out as soon as he could and take it aloft for close examination. He also wanted to know what I was doing here and who I was and where I'd come from and he was going to subdue me if he could and similarly take me to the surface and hand me over for interrogation.

There'd been a chance that I might have capitulated in the instant of encounter but the time was past now and he agaisnt mysaw that. The very fact of my standing here face to face with him was an expression of hostility and he was going to make the first move: by infinite degrees he was bringing his body lower and turning the trunk with the right shoulder coming towards me and the elbow at right angles, the blade of the knife cocked and steady, dull silver in the strange underwater light.

Combat at eighteen fathoms has its own rules and some of them run counter to the norm: you don't draw back to bring momentum into a blow because the pressure of the element is going to kill off momentum anyway. You have to streamline the strike and he did that and the blade hit the glass of my faceplate and the point stayed there scraping on the surface as I held his wrist and we looked at each other, locked and motionless. He'd struck directly forward and into the aim and I'd known he'd have to do that because it was the only way and I'd worked fast and my forearm had driven straight upwards to connect my hand to his wrist but the water had built up resistance against the bicep area because it was travelling at right angles and it had slowed the blow but not critically: he'd struck for the throat or my breathing tube and hit the faceplate and his wrist was locked in my fingers and I began squeezing.

The bone was thin and I began levering, working for a fracture, watching the pain start in his eyes. A foot blow was out of the question because of the drag of the fins so I knew he'd have to use his left hand and I was ready but he was wickedly fast, clawing for my breathing tube again and again as I jerked my head back and kicked upwards from the sea bed and dragged him with me, keeping the pressure on his wrist: but we were clear of the sand now and fighting in the manner of fish, and he used the element for his own defence, letting my grip on his wrist move his whole body, the kinetic energy travelling through the arm to the shoulder and beyond.

Breathing became difficult as the muscles demanded oxygen: the lungs began creating a vacuum, setting up pressure lag at the regulator.

He had stopped his left-hand action because I was holding the air tube out of his reach, my back arched and my head angled, but this was defensive because my right hand was immobilized and time was already running out: in scuba diving exertion of any kind is at a heavy premium and we were making demands on oxygen that weren't going to be met. I estimated we had two more minutes before exhaustion set in.

The current was taking us slowly away from the substructure of the rig and we were drifting higher, with the sandbars below us losing definition. The only purchase either of us had was against the other's body and we were using our legs now, not for striking but for leverage, my right foot working for pressure against his neck as one of his legs was hooked suddenly around mine as he went for a knee lock and got it and began putting stress into the movement with our ankles braced together bone on bone.