Even with the engine at full speed there were times when Esmerelda began to drift back towards Falcon, caught in the grip of a cold water current as it rushed in to replenish the vaporized water. An occasional eddy swung her round by the bows and Geordie had to take her out in reverse.

It was three hours before we were well clear of Falcon, a mad jumble of fire, steam, smoke and lava falling mercifully astern of us. Geordie had been spelled at the wheel by Ian and Taffy; the rest of us had managed to extinguish the fires, hurl – the worst of the debris overboard, and bring some faint semblance of order to the ship. We took turns to collapse with exhaustion. Clare worked steadily taking care of burns and wounds.

Some parts of Esmerelda were in better shape than others. By a strange miracle the launch still clung to our coat-tails, though we had no time to stop and haul her up on davits. I found to my great relief that my notes and the bulk of the lab files were in order, though most of the apparatus was wrecked. It was better to work on things like that than to dwell on the last appalling few hours. But there were a couple of matters that had to be taken care of, that could not, for all my wishing, be put off much longer.

Mark was still on board and had to be dealt with.

And so was Hadley.

Taffy had started to tell me, just before Falcon blew its top. Hadley had been one of the two men who had leapt to our deck, and was being held in the brig with the other men from Sirena. It was dismaying to know that he was with us, but for me the most serious problem was Mark.

He and Paula had stayed together in the saloon during the, whole of the encounter with Falcon. Now I had to face him. I pulled myself to my feet and went wearily below. Paula looked up as I entered and her face, like everyone else's, was drawn and shadowed.

'Are we safe yet, Mike?' she asked.

'Pretty well. You should both come up on deck and get some air. It's remarkably peaceful up there now. Paula, thank you for standing by.'

She smiled a brief acknowledgement and she and Mark got up together. He was very pale under the heavy beard, and limped a little, but he seemed fairly strong. He had said nothing as yet. I led the way on deck and they followed in silence, numbed by the sight of so much damage. Nobody spoke to Mark, but more than one of the crew reached to pat Paula's arm or give her a quick smile as she went by.

We stopped outside the deckhouse, a shattered and burnt-out shell. They stood together looking astern at the now distant ascending cloud of smoke.

'I wish I'd seen it,' Mark said. He sounded wistful.

'It was fantastic, but too close for comfort,' I said. 'I'm going to tape my impressions as soon as I can. There's a lot to be learned from such close-up observation. Do you know what happened to Sirena?' 'Clare told us,' Paula said, and shuddered. Mark seemed unmoved. He was not going to be overtaken by conscience as easily as that. I didn't mention Hadley or the other prisoners.

'Mark,' I said abruptly, 'I have to talk to you.'

'I'll go,' Paula offered.

Mark took her arm and held it. 'Stay with me,' he said. She was the only one he could be sure was on his side, and he needed a friend at court. He turned to me and a hint of the old arrogance was back in his voice. 'What's it going to be? One of your little lectures on decency?'

I felt grim and tired. This wasn't going to work.

'For God's sake, Mark, ease off. I'm not going to lecture you – it was always too late to get you to listen to reason. But we have to work something out before we land, or before someone sights us.'

I wanted above all things to lie down, right there on the deck, and sleep for a week. I was physically beat up and exhausted, but the onus of Mark was a heavier burden. I wished I could have had Clare to stand by me, as he had Paula, but I wasn't going to bring her into it.

We stared at one another in stalemate.

My jumbled thoughts were interrupted by a bubbling scream. The sound came from below. Taffy and a couple of the others dived down the companionway, and Ian came past us at a run. I made a move to follow but then held back, leaving it to the professionals.

I said, 'I think it's one of the Spaniards. He must be hurt, poor devil.'

'What Spaniard?' Mark asked.

For answer there was a crash from below, and Hadley burst into view through the burnt-out galley and onto the deck where we were standing. He had a kitchen knife in his hand. I backed away from his red-rimmed crazy eyes as he came at me like a bull.

I booted him on the shin but it was like trying to stop a truck. He leapt on me in a bear hug that jarred excruciatingly on the knife-graze in my side. His knife hovered near my throat. Desperately I clawed at his face as we fell. Hadley landed on me with all his weight but thank God his knife-arm was pinned beneath us. I chopped viciously at his throat and he choked. His grip loosened. I jerked a knee up into his crotch and broke free.

But Hadley recovered fast and rolled over onto his feet. Agile for his bulk he leapt on me as I gasped for air. He pinned my arms and I felt the breath being squeezed from my lungs and a rib cracked agonizingly. Blackness surged in front of my eyes.

Suddenly he lost his balance and we both crashed to the deck. Nick, crawling up from behind, had seized Hadley's ankle and had yanked his foot out from under him. I rolled free and Hadley got the full force of a bullet from Ian's gun in his belly.

Astonishingly he regained his feet and swooped for the knife which lay on the deck. For a near-fatal instant we all stood paralysed. With an unearthly bubbling scream of rage and agony he plunged towards Mark and the knife flashed viciously in the sunlight.

Mark flung Paula aside and met the attack full on. The knife sank into his side and he collapsed without a sound.

The weapon fell to the deck. Hadley took two staggering paces backwards, clutching his stomach, and then in a full back arch he went over the railings into the sea.

Silence hung in the air after his fall.

I stood shakily clutching my ribs and breathing in short painful gasps. Clare and Bill Hunter were first at my side. When Campbell went to help Paula, she brushed him aside and ran to Mark, who was still lying on the deck. But he was conscious and trying to sit up.

Geordie arrived at a run and a babble of voices told him what had happened. Taffy said harshly, 'My fault, skipper. I let the bastard out. We heard a man screaming and I thought someone was in pain in the brig. I went in with Bill but Hadley went through us like an express train.'

Bill said, 'No wonder that poor devil was screaming. Hadley had near taken the arm out of his socket; to get us to open up.'

'He was quite mad,' said Ian soberly.

To dispel the air of gloom Geordie said briskly, 'Well, he tried and he failed. And that's the last of them. The others won't make any trouble. Now, lads, back to work. We're not home and dry yet.'

They dispersed slowly. Geordie turned to me and said softly, 'The last of them – bar Mark. What are you going to do about your brother, Mike?'

I looked at him bleakly.

'I don't know. First I must see how badly he's hurt. But I can't just hand him over to the police.'

'I don't think you've any choice, laddie.'

'I guess not. But it's a hell of a thing to have to do.'

Clare, her arm comfortingly firm around my rib cage, waited in silence for me to come to a decision. I said, 'Geordie, I have to talk to him alone. Take Paula with you, Clare. Look after her. God knows she's had enough to cope with. Keep everyone away from us for a while, would you?'

'I'll do that,' Geordie said.

Clare gave me a smile of compassion and warmth and then walked back to the deckhouse. Mark was sitting propped up against the railing with Paula as always by his side. I waited until Clare took her gently by the arm and the two girls went below to join Campbell. I wanted to speak to Mark, perhaps for the last time, with no one to act as a shield between us.