I switched my gaze back to the port and caught my breath. There was a face out there. An eye winked.

Bill Hunter was back on board.

He was a hidden ace that Ramirez must not become aware of. I cautiously lifted my hand to my mouth, coughed, and then made a slow downward movement, being careful not to jerk. I didn't want to catch anyone's attention. The eye winked again and the face disappeared.

Campbell was still speaking, desperately searching for arguments to persuade Ramirez not to go ahead with whatever plans he had for us. Again there was that vibrancy in my ears, a curious beat in Campbell's voice as though there were some sort of aural interference, some note so low as to be inaudible. Not far away there was a sound as though an engine were letting off steam. Esmerelda shuddered and the noises on deck increased suddenly.

Ramirez interrupted Campbell, turned and to my horror strode over to look out of a porthole. I tensed but then he turned back and spoke again, and I realised he'd not seen anything untoward.

'Whatever is going on out there will serve its purpose,' he said coolly. 'As soon as these idiots of mine have parted the two ships we go our separate ways. You won't have far to go -a mile or so straight down. We will tow you into deep water -or point your nose into that thing out there.' He turned on Geordie. 'We have borrowed an idea from you, Captain. We will set an explosive charge against your hull, and that storm out there will do the rest.'

Geordie ground his teeth together but said nothing.

Somebody ran across the deck over our heads and a voice called out. Ramirez cocked his head and glanced upwards. 'It sounds as though they are about ready.'

I heard a clatter of heavy boots on the companion steps and there was a thump on the door. At a gesture from Ramirez one of the guards opened it and Hadley came in. He looked at us with an oafish grin that didn't reach his pale, cold eyes and bent to whisper to Ramirez, who immediately turned to look out of the porthole again. I thanked God that Bill had kept out of sight. Or had he?

Ramirez turned back. 'Which would you choose? Deep water or Falcon Island? There seems to be increased activity over there.' He smiled and said to Mark, 'This is lucky, you know. Where else should a survey ship be wrecked but in investigating Falcon Island a little too closely at the wrong time? Keep our friends happy for a little while.'

He turned on his heel and left the saloon, followed by Hadley.

Geordie watched them go and then transferred his attention to Mark. 'You're a poor specimen of a man,' he said with contempt. 'What makes you think I'm going to sit back and let you wreck my ship and murder my crew? If I'm going to be killed I might as well take you with me.' He began to rise from his chair. With Ramirez's departure a curious change had come into the atmosphere. It was as if we could all recognise that where Ramirez had real authority and total amorality, Mark had only his ego and his self-seeking veneer of toughness over a very insecure personality.

As Geordie started to rise Mark snapped out a command in Spanish and the guards' rifles lifted to the ready. 'Be careful,' Mark said. They are trained killers.'

'So am I,' said Geordie with menace. He continued to rise slowly and Ian started to get up as well.

Mark spoke again in Spanish and one of the guards casually fired his rifle, apparently without aim. The noise was appalling and we flinched back as splinters flew from the bullet as it struck the cabin sole just by Geordie's foot. He hesitated and I spoke sharply. 'Cut it, Geordie – you haven't a chance. You can't move faster than a bullet.'

Geordie glared at me under his lowered brows but I made a quick slashing gesture with my hand and, taking a chance, winked at him. His brow smoothed and he sat down again, as did Ian. Both were watchful, and I knew that I had succeeded in alerting them.

There was a sustained racket from overhead. Geordie said, 'They're making a muck-up of it out there, aren't they?'

'Mind if I smoke, Clare?'

I put my hand into a pocket and stopped as a rifle barrel turned and the muzzle pointed unwaveringly at me. 'For God's sake, Mark, can't I even have a cigarette?'

He looked amused. 'Smoking's bad for you, Mike. Go ahead – but you'd better have nothing but cigarettes in your hand when you pull it out.'

Slowly I withdrew my hand as he spoke to the guards again. The rifle barrel drooped a little and I opened the packet and put a cigarette in my mouth. And at that moment I saw Bill's face at the port once more. The sound of the rifle had brought him back, as I'd hoped it would.

The saloon door opened and there was a brief exchange between one of our guards and a man outside, and then it closed again. Clearly Ramirez too had sent to ask about the shooting. I put my hand to my pocket again and said to the man with the rifle, 'Fosforos?' He made no sign and I managed to get the matches out without being threatened.

I lit the cigarette and said, 'Look, Mark. You know everybody cooped up in this saloon. Some have been your friends -others have been more than friends – a lot more. In God's name, what kind of a man are you?' I found it hard to speak to him without my voice betraying me.

'What can I do?' he asked petulantly. 'Do you think I want to see you all killed? It's out of my hands – Ramirez is in control here.'

Clare's voice was cutting. 'He washes his hands – the new Pontius Pilate.'

'Damn it, Clare, you don't think I want to see you at the bottom of the sea? I can't do anything, I tell you.'

Campbell said, 'It's no use, Mike. He wouldn't do anything to save us even if he could. His neck's at stake, you know.'

This was my chance. To speak to Campbell I had to half-turn away from Mark and the guards in a natural fashion. 'He'll join us anyway,' I said. 'Ramirez has got what he wants now. He doesn't need Mark any more – he only needs to take my notes with him – and I'm damn sure he'll want to rub out any witness to all this – including Mark.'

I was printing on the back of the cigarette packet with the stub of pencil I had taken from my pocket with the matches. The words, as large as I could make them, were 'CABLE HOLD'. I drooped my eyelid at Campbell and he caught on fast. He shook his fist at Mark to divert attention and started acting up a little. 'You damned murderer!' he shouted.

'Shut up,' said Mark venomously. 'Just shut up, damn you.'

I held up the cigarette packet towards Campbell and said, 'Take it easy. Have one?'

'No, no,' he brushed my offer aside, but the job was done, and Bill had had a clear vision of my message over Campbell's shoulder. I hoped to God that he had good eyesight. Clare saw the message too and her eyes widened. She bent her head over the still prostrate Paula to hide her expression. I saw her whisper in the other girl's ear, apparently still soothing her.

I said to Mark, still playing for time, 'Why the hell should he shut up? We've got nothing to lose by telling you what we think of you. I'm sickened at the thought of you being any kin tome.'

Mark's jaw tightened and he said nothing. I had to goad him into speaking. I risked a glance at the port, and saw that the face had gone, to be replaced with a hand. The middle finger and thumb were joined in a circle. Bill had got my message.

Whatever happened now I had to give him time to act on it. Now he knew where the rest of us were and might be able to do something about it. I wondered if he was alone or if Jim and Rex were still with him. It was a slim chance but it was all we had. I reckoned that the only thing we could do to help was to get at Mark in some way – and in his highly nervous state that might prove deadly dangerous.

I said, 'What put you on to us? The sea's a big place, Mark. But of course you always knew where that high-cobalt nodule formation was, didn't you?'