Black Fish's vessel, the Seagull, lay at the far end of the Barbican, not far from the stone set up to mark for all time the berth of the Mayflower before she had set sail across the Atlantic to New England with her cargo of Pilgrim Fathers. Beneath her grimy appearance and chipped green paintwork, she was a handy little sloop with well-caulked seams and a snug cabin into which, on Black Fish's orders, Marianne descended.

'You stay there, and not a sound! We don't want to tell the coastguards we're here.'

He turned his attention to the sails and the little vessel slipped slowly out of harbour. But, to the not inconsiderable surprise of his passenger, instead of making for the open sea, Black Fish turned up the estuary of the Tamar in the direction of the naval dockyard. Curious as to the reason for this behaviour, she crawled on hands and knees out of the cabin and whispered: 'Where are we?'

'I told you I've something to do. Another passenger to take on board. Now, that's enough. One more word and its down to Davy Jones with you!'

He was stowing the sail as he spoke and now produced a great oar with which he began sculling noiselessly but with an effectiveness that did honour to his strength. Now that they had left the beacon behind them, the darkness was complete, only pierced now and then by the distant riding light of some vessel. At night, the tower crowned with its glowing brazier was a fantastic sight, but Black Fish had made a considerable detour in order to avoid the stippled red light thrown on the dark water. Clinging to the rail of the tiny vessel, Marianne breathed in the night air greedily and stared at the ghostly shapes of the hills gliding past with the occasional bright point of light. The sloop worked slowly up the estuary, fighting the current. It was not long to high tide and the swell was already making itself felt in a short, choppy sea. Black Fish must be straining every muscle but he was a man of uncommon strength, well able to do the work of two. Marianne thought that he must also have cat's eyes to find his way in such conditions, although now that her own eyes were becoming accustomed to it, she was able to make out some small shapes.

Abruptly, as they passed the crumbling stonework of an old, disused mole, Black Fish stopped sculling, shipped his oar and tied up to what must have been an ancient ring in the wall. Seating himself in the stern, he cupped his hands about his mouth and mewed three times like a gull, with a realism which astonished Marianne. After that, he seemed to listen for something.

Marianne, full of curiosity, was about to speak, but he waved her curtly to be silent and she subsided meekly.

It was getting colder and there was something forbidding about the darkness and silence of their surroundings. Not far away, a number of dark shapes loomed up looking like a barricade of huge ships lying across the Tamar. Even the slap of the waves had stopped. The monsters lay huge and motionless, a lantern burning here and there, and the water in between them and the sloop looked curiously flat, smooth and thick, like cream. It gave off a faint smell of mud. Unable to contain her curiosity any longer, Marianne crept closer to Black Fish and in spite of his prohibition, whispered softly: 'What is it? Where are we?'

Black Fish pointed to the dark shapes.

'The hulks,' he said simply. 'You know what they are?'

Marianne knew, she had heard of the old ships, no longer seaworthy, with their barred ports, that were used as prisons to house those of Boney's sailors who fell into English hands.

'Admirable prisons,' Aunt Ellis had been wont to say with satisfaction, 'only too good for them, I dare say! They say some manage to escape—'

But what were they doing here? Why this mystery? Black Fish was speaking again in a low voice.

'The Europa, the St Isidore, the St Nicholas, each one of them a hell! The French are crammed in there so tight that every night some die of suffocation—'

To her surprise, Marianne heard a note of anger in the big man's voice and she did not hide her astonishment.

'But they're enemies! You ought to be glad. But it seems to grieve you.' The beginnings of an oath escaped Black Fish but he controlled himself at once and only said gruffly: 'I am a seaman, not a jailor, and they too are seamen—'

Suddenly Marianne understood.

'Do you mean – you are going to help one of them to escape?'

'Why not? He is like you, willing to pay. I'm helping you to escape. So keep your questions to yourself. Now, keep your trap shut or you'll have us spotted.'

Marianne did not persist. She was made forcibly conscious that now she was only a girl, like any other, less than others even, because she was obliged to hide and flee. She had no choice but to accept, humbly and in silence, what fate might send her, even to being ordered about by someone who was practically a pirate.

But in a moment, her thoughts were distracted by something very odd that seemed to be happening. Something appeared to be crawling towards them over the water. Marianne could not make out what it was precisely. Again, Black Fish imitated the gull's cry softly beside her and she almost cried out. There was something frightful and terrifying about the blurred form spread-eagled on the water. She pointed with a trembling hand.

'There – do you see?'

'Quiet. It's him.'

Marianne's eyes were by now sufficiently accustomed to the darkness for her to be able to see that the figure was in fact that of a man. She was about to ask another question when Black Fish prudently forestalled her by whispering hastily: 'The hulks are anchored in a muddy creak. We're at the edge of a lake of liquid mud. It's a death trap – if he tries to stand up, the mud will suck him down—'

This time, it was fear that kept Marianne silent. Her heart was in her mouth and her eyes wide with terror as she followed the fugitive's agonizing progress. The first hulk was not very far away but to her the distance seemed immense, and then there was the additional danger that the prisoner's flight would be discovered or of his being overcome by cold in the water. The man must not be recaptured because if he were, she would be taken with him. He must succeed for her own life to be safe. Moreover, in her heart of hearts, she admired the courage of a man, who, to regain his freedom, would risk a hideous death in the slimy depths of that perilous sea of mud.

Black Fish, paying no more attention to her, was bent over the rails, leaning as far out as he could and holding the oar at arm's length.

He gave the gull's cry once more, then Marianne heard him whisper in French: 'Over here, lad. One more heave-there you are!'

There was something so timeless and improbable about the whole of this night that now she was no longer even astonished that a one-time English pirate should express himself with perfect familiarity in the language of Voltaire. It was no stranger than everything else. Nothing, in any of the books that she had read, not even Robinson Crusoe itself, had been anything like this.

She heard the sound of someone gasping for breath, followed by a muffled, wordless cry and then the boat lurched violently. Black Fish came upright hauling after him, as though dredged from the bottom of the sea, something heavy, wet and slimy which he deposited upon the deck where it lay motionless. But for the rattle of the man's breathing, Marianne would have thought him dead. Without wasting a moment, Black Fish took him by the feet and dragged him towards the cabin. Marianne, listening eagerly, overheard a scrap of dialogue, likewise in French.

'Not too bad, was it?'

'No. I've known worse, but we must be away from here – I think a spy saw me go! Oh God, it's cold!'

'Here, wrap this round you. When you're dry, I'll get you some clothes. And take this. There's rum in the flask – then try and sleep. We'll get off now. Tide's all but full.'

In fact, Marianne noticed a tremor of the ship's planking where she lay at the edge of the mud, as though something were working and writhing below. Black Fish reappeared, cast off and shoved the boat away from the old jetty with a strong push of the oar. Not before time. Lanterns were moving like will o' the wisps about the hulk and a light shone out through barred portholes, revealing gesticulating black figures. Soldiers could be seen, trailing their guns. But the sloop, freed from the mud by a lusty stroke of the oar, was already passing behind the crumbling stone jetty, back into the main stream of the Tamar. Black Fish stuck to his oar, rowing like a trojan, and now, with the current in her favour, the light vessel was making a good speed. Marianne watched, fascinated. The man was like some fantastic human machine and thanks to him the heavy ship seemed endowed with an extraordinary driving force. She was just passing the beacon, lying well out in the middle of the estuary, when the gun boomed out behind them. Black Fish cursed without troubling to keep his voice down.

'A thousand thunders! The escape's discovered! We're lucky though, wind's getting up—'

It was doing more than getting up, it was blowing with a force that Marianne found terrifying. Suddenly, the estuary had become huge. The shore line had receded on either hand, leaving a broad expanse of sea, the waves capped with curls of foam. Imperturbably, Black Fish set the sail and took the helm. The sail gave a crack as the wind caught it and swelled triumphantly. The sloop bounded forward, running for the open sea. Once past the final buoys and nothing but the wide waters lay before them. The echo of the gun was lost in the roaring of the wind.