One minute.

Sometimes a bubble rose from the sea bed, turning dull silver and then shimmering past my face, vanishing above me. One of them passed close to a mine not far from where I moved: it touched and broke against the tip of a copper horn and for an instant sent me mad as the firestorm roared raging through my head. Then it was over: the sound died away and the seas subsided and hollowed echoes of my breathing slowed again. The potential packed inside these deadly fingers had grown too much on my mind and I wanted nothing to touch them: not even a bubble.

Zero.

02.30.

Break-off point. I'd been searching for half an hour and hadn't seen anything and this was the time when I must break off and let the stuff go on drifting. Beyond this limit I'd start using the air that was reserved for taking me as far as Heng-kang Chou if I had to get out of the target zone and go to ground. I'd covered most of the minefield and drawn blank: in daylight I would have seen the loose gear long before this but I'd been working in near darkness and without a hope of using the lamp because the mines were cabled on outriggers below the surface, well clear of the rig's substructure, and if there were look-outs posted on deck they'd pick up the glow of the light.

Twice I'd doubled back on my tracks without knowing it until I'd seen the faint image of a pontoon leg on the wrong side, a hundred feet below, and realized I must have turned too far where the mines made a right angle. Once I'd wasted time going down to fifty feet, seeing a patch of shadow that had turned out to be a mass of drifting weed.

I turned obliquely and dived in a long curve, coming up inside the minefield and heading for the great trellis of girders, hearing the sound when I was almost halfway across the open space. It was the sound of a ship's bell, cracked and muted, its rhythm irregular. In five minutes I had the direction worked out, turning full circle to orientate aurally and then moving across the slow southerly current and through the network of girders to the far side, reaching the minefield again.

I didn't have to search far, once I'd got there. The stuff was looming in front of my faceplate, stationary except for the slight tug of the current. The nylon cord had fouled one of the cables and was wrapped around it, and the sound of the ship's bell was being set up by the valve of one of the reserve tanks as it kept hitting against the mine.

I stood off, watching it, my hands fanning gently to keep me upright. The waterproof bag containing the radio and the rations was creating resistance against the current: part of it had caught around the cable, leaving one of the tanks to swing against the mine. It wasn't any good trying to make an estimate and work on its findings because there were too many unknown factors but it didn't look as though I had long because the shoulder of the cylinder was nudging one of the detonation horns and it was a strictly shut-ended situation so I kicked with the fins and moved in, freeing the cord first and then working higher up, keeping my head back and the faceplate clear of the horns as I pulled the reserve tank clear. It wasn't easy because the mine was fixed to its cable with a turnbuckle and cotter pin and the pin kept catching against the valve-guard.

Normal thought process had ceded to a form of specialized attention: the conscious field had narrowed to contain only the essentials I needed to work with - the shape and size of the valve-guard and the cotter pin and the horn of the mine, the angles and direction in which the manipulation had to proceed, the forces against it and the means of combating them. But somewhere in my head there was panic trying to get loose, like an area of pain the anaesthetic hasn't quite reached.

Ignore.

This thing wasn't long out of the armament factory: the steel had a satin sheen and the copper of the horn was catching the glow of the flare pilot burning above the rig. The cotter pin was bright and a blob of grease still clung to the thread of the turnbuckle. There were Roman characters indented around the rim of the mine itself: they weren't clear in this light but it looked like Hitachi, Japan.

The valve-guard came free and I backed off, bringing the gear with me. The time was 02.51 and I was alive and the mission was still running.

Just after 03.15 I went aboard the rig.

The storm-wave height of the lower deck was fifty feet, leaving a gap between the deck and the surface of the sea; but in this area it was almost dark and the girders gave a network of cover. I left all four tanks and the rest of the scuba gear lashed to a girder below surface and climbed one of the iron ladders. I didn't expect to find look-outs on this first deck: they'd be surveying the open sea beyond the limits of the minefield. There was a radial series of catwalks and I took one of them as far as the central ladder that served the drilling complex, going up again and reaching the top deck.

A single main lamp burned alongside the derrick, flooding most of the deck. A blizzard of bright moths blew around it and a lone bat circled, gorging itself, sometimes rising to the height of the flare pilot flame and circling again. Most of the deck was taken up with the drilling rig, skid mounted and abutting on the control cabin. The turbines took up the rest of the space and the helicopter pad was raised on a separate platform clear of the derrick and the two auxiliary pedestal cranes.

There were more radio facilities than I'd expected: two masts cantilevered off the top deck and carrying microwave dishes, and a third mast with a booster-type unit that looked very like a tropospheric scatter system, conceivably for data transmission, rig-to-shore.

The one on my left hadn't moved for three or four minutes: he was using binoculars on the sea through a ninety-degrees vector. The other man was pacing, his back to me because I was in the central area and he wasn't looking for anyone there. They were both in some kind of paramilitary uniform but carried only sidearms. The deck was three or four hundred feet across and I assumed there were other look-outs on the far side of the derrick and to the south of the engine-room installations.

It took me nearly an hour to locate the control console, not because it was far from the central area but because I had to move by inches, getting back into cover and staying there for minutes at a time while a look-out patrolled the area I was working. I couldn't have moved around at all if the cover hadn't been exceptional: the whole of this deck was broken up by cranes and winch gear and power houses, and most of the enclaves were in deep shadow. The dangerous areas were the catwalks and corridors and I kept out of them except when I had to evade one of the patrols. The cover story Ferris had worked out for me was better than nothing but it wouldn't stand up to professional interrogation: it was an extreme resource to keep the opposition stalled while I tried for an emergency get-out from the target zone.

If one of those patrols sighted me it could blow Mandarin as effectively as a mine.

The control console was housed in a building like a concrete bunker and the only window was made of smoked plate glass with an integral mesh of extruded steel. Lamps burned inside and the control panels were visible through the glass but the place didn't seem to be manned at this hour. The signs above the main door were in Chinese characters followed by a number.

It was now an hour before dawn and I began getting out, hanging back in deep cover and moving only when the risk was calculated. The most interesting thing on the middle deck was the work site where they were building some kind of platform into the main structure of the drilling derrick: the area was cluttered with welding gear and pneumatic rivet hammers and there weren't any signs that the job had been abandoned. I had to signal Ferris and I couldn't do it from anywhere near the rig unless I had adequate noise background to cover my voice and if those riveters started up I could get some sort of message out through the interference if the set was any good.

By 08.00 hours I was beginning to feel the shakes.

I had a lot of information for London and I wanted to give it to them as soon as I could because the future wasn't too certain. But I couldn't do anything about it until I had some kind of noise background and all I could hear was the low-pitched sound of the diesel generators and that wasn't enough: the human voice range would cut right across it.

There were two things wrong: geometry, chronometry.

They wouldn't leave a minefield to look after itself: there'd be a strict surveillance routine to make sure none of those things got loose or trapped flotsam and that meant they'd be sending someone down in daylight and he'd use one of the four iron ladders that ran from the lower deck to the sea bed down the substructure legs. They provided access to the pontoons and anchorage for repair and maintenance and the trouble was that I couldn't hope to find any effective concealment here between the lower deck and the surface of the sea. The geometry was wrong.

I was wedged in the angle formed by three girders and it was the best cover I could find anywhere in the stormwave gap between the rig and the water: there were twenty other places like this but they were exactly like this and therefore no better.

If the work crew on the middle deck had started riveting at first light I could have sent my signal to field direction and got out. I'd been thinking of Heng-kang Chou Island in terms of a refuge in emergency but now I'd surveyed the rig I knew I'd have to go out there and hole up till tonight if London wanted me to extend operations: but I couldn't leave here before I sent my signal because the waterproof bag was showing some wear and tear and I didn't think I could get the Hammerlund as far as the island in working condition. One drop of sea water in the wrong part of the circuit could block off the information I had for London and there might not be another chance. So I had to stay here and hope the riveters would start work before anyone came down here to look at the minefield but they hadn't started work yet and that was why I was getting the shakes: the chronometry was wrong.

At 09.00 I was sweating hard in the rubber suit with the sun eight or nine diameters above the horizon and sending out heat. There had to be a change of plan because I was a sitting duck and the best thing to do was leave the radio here and go down and put on the scuba and wait with my head above water, ready to submerge as soon as anyone came down from the deck. They wouldn't see me and wouldn't see the radio unless they were looking for it and I could stand off below water and get back here when I could. One of the things I didn't like about it was that I'd use up a lot of air but none of the arguments against this plan made any sense because if 1 didn't put it into action I risked being seen and taken on board for interrogation and the longer I waited the higher the risk would become.

I tilted the Hammerlund along the inside line of rivet heads against the girder and swung down and went sideways along a horizontal section till I reached a pontoon leg three feet above the surface and then climbed all the way back because the noise had started.

09.14.

Frequency 8MHz.

222.

Executive in the field to base: Wing to Swordfish.

A hell of a bloody din from the deck above me, louder than I'd expected, the rivet-hammer trapping the sound and sending vibrations throughout the whole of the rig: I could feel it against my thighs and shoulder as I slid one leg along a girder and lay almost prone with my head against the set.

222-222-222.

He'd told me he was going to stay on board Swordfish until I could send Him a situation report: Ackroyd had a much bigger radio than anything Ferris could carry around and I might flash the sub to come and pull me out in a hurry and he'd want to be there.

I kept on talking, giving them blocks of three with my head against the set and my nerves getting tight because it was going to be a fifteen-minute exchange of signals and I hadn't even raised an acknowledgement yet and as soon as anyone came down one of those ladder the whole mission was blown.

Treble two thrice.

All right, I was in the middle of seven thousand tons of steel girders waving a six-foot aerial around and trying to hit the ether with it while half a dozen diesel generators were pushing out enough electrostatic squelch to jam any transceiver within ten miles of here.

222 - 222 The riveter stopped and I hit the volume control in case Swordfish came through too strongly. The squirt of the welders kept up a low background so I thought I'd try it and spoke right against the mike, treble two, three blocks. Why the hell didn't those bastards - 345-345-345.

Swordfish.'

Very faint. I acknowledged and turned up the volume a few degrees and waited. They were going to get Ferris. He wouldn't be far away. He'd give me fives: that was Mandarin. Sweat stinging my eyes. Nobody on the ladders. Oh for Christ sake come on, we're 555 - 555 - 555.

Mandarin., I went straight into the spiel.

We'd been Control-briefed to exchange signals totally in cypher when we were using the Swordfish radio, without any speech-code thrown in to expedite the transmission. The Admiralty was a bit edgy about having spooks on board one of Her Majesty's ships and they'd obviously told London that if we wanted to use the sparks we'd have to do it in strict hush. That was fair enough: they weren't used to having a couple of torn-arsed mudlarks playing about with their sub and the kind of stuff we'd be sending was pretty strong compared with the day-to-day signals normally going out-Have polished anchor - Please send buns for captain's birthday - so forth.

489-356-181.

Ferris was asking how I was and I told him to shut up and listen because I wanted to give him the whole picture before anyone came down here and stopped me.

389-376-210 . . . Extending and reversing, leaving some of the transfers the right way round whenever they could stand in as a contraction... This isn't an oil rig it's a missile base... thinking up non-standard contractions when I thought Ferris would get it first go without risking delay while he queried it . . . No well-head and false flare stack and crude reservoirs . . . image from air would be perfect . . . basic armament for defence: six eight-inch naval guns camouflaged as lean gas coolers . . . main structure under modification . . . electronic and telemetric installations not yet completed . . . assume Tewson involved as technician or supervisor . . .

'Him and his slide-rule,' Nora had said.

Ferris shot me a couple of queries about crew strength and the type of missile and I told him I thought there was only a skeleton unit on board while the boffins sorted out the stuff for the console. I couldn't tell him anything about the actual missile except that I hadn't seen any exhaust ducts or heat shields. There might be Then the riveter started banging again and I nearly fell off the bloody girder and Ferris began complaining about the interference: the generators had been bad enough but this din was affecting the air acoustics as well as the signal and I was getting fed up.