Thank God I did as he told me and kept my mouth shut. Not two minutes later, a dozen soldiers suddenly appeared out of the darkness right in front of us. Light in the tunnel was so scarce that, even in their bright red uniforms, they were hardly more than shadows. Yet these shadows were armed, and looking none too pleased.

‘Are the Ching Chongs[52] still at it?’ one growled.

‘Ye bet they are!’ another answered. ‘Damned yellow bastards! Not a night when they can’t get to bed like decent folk. And it’s the likes of us that has to…’

They went past us, and soon their voices vanished into the distance.

So the Dance of the Dragon was still going on outside, was it? I felt suddenly cold at the thought of what exactly the soldiers had been ordered to do. Why were they marching, as I was sure they were, out into the street to where the Chinese were dancing? I sneaked a sideways glance at Mr Ambrose’s profile in the gloom. It was too dark to really see his face. Was he feeling the chill inside, too?

Dumb question. He probably was constantly at a core temperature of - 100 degrees Fahrenheit.

Up ahead, there shimmered a faint light again. Not yellowish light this time, though, but cold, blue light. The light of the moon. As we came closer, I saw that it was falling into the tunnel through tiny cracks in a wooden wall - a wooden wall that ended the tunnel.

I opened my mouth to ask ‘What now?’ - but Mr Ambrose threw me one of his special looks, and I closed it again. He stepped closer to the wooden wall, which in spite of the few strands of moonlight, was utterly black, and let his hands skim over it. About halfway up the wall his searching hands suddenly stopped. The fingers closed around something, pressed, and pushed.

The door swung open, revealing a view of a narrow stretch of water, and a harbour wall, half covered in algae. Distantly, I could hear the sound of the Dragon Dance, and I was relieved that it sounded as if all the dancers were still alive and perfectly fine.

‘How did you know there was a doorknob, Sir?’

‘When you have a secret passage that nobody is supposed to be able to find from the outside, it rather makes sense to have the doorknob for the entrance on the inside, don't you think?’

Now that he said it, it sounded rather obvious. But then, how the heck would I know? This was my first secret passage ever, after all! Was it his first? I looked at his face, hard and implacable in the moonlight. Probably not.

Carefully, he leaned out of the open door, his eyes flicking to the left and right without his head moving an inch. In a moment, he was back inside the tunnel, right beside me.

‘No guards around,’ he said in a low voice.

‘Do you think that we’ve somehow gone the wrong way? That the file isn’t here at all?’

‘I doubt it. Look.’

Imitating him, I carefully stuck my head out of the door and let my eyes flick to the left, then to the right. There it was! To the right, a narrow catwalk, hardly more than a ridge, led along the harbour wall. It disappeared behind the bulk of a sleek, rather small ship with only two masts. It would have been completely unremarkable, if not for the dark, even colour of its hull, which was unlike that of any ship I had ever seen.

‘You saw it?’ he asked, when I ducked back into the tunnel.

‘The catwalk? Yes. Cleverly done, that. You probably don't even notice it from up at the docks. And even if you do, what’s the significance? But down here, you can sneak from the tunnel to any ship in the dock without anybody seeing.’

He nodded. ‘Yes. But it’s not the catwalk that worries me. I knew it would be there.’

‘Really? But you are worried?’

‘Yes.’

‘Why?’

‘It’s that ship. I think it may be…’

From behind us, out of the tunnel, we suddenly heard the sound of approaching feet in lockstep. The sound grew louder.

‘Quick!’ he hissed, pushing me out of the door and onto the catwalk. ‘Onto the ship before they see us and think of asking questions!’

Suddenly, I stood in the moonlight, open and exposed. I prayed to God that there were no guards on that sinister black ship. But even if there were, what was there to see? Just another one of their own soldiers, I hoped. At the moment, however, I didn’t feel very soldierly.

Behind me, I heard the door shut with a click.

He’s out, I thought. He’s behind you, and he’s expecting you to move! Go on! Move your generous behind, he’s relying on you!

And somehow, my feet, which just a moment ago seemed to be frozen to the wood of the catwalk with icy fear, started to move. The black silhouette of the ship loomed above me, its masts and ropes throwing a spider’s web of shadows across the way in front of me, a web in which I would soon get caught.

I entered the web of shadows, and my heart went cold. Around the curve of the ship’s hull appeared the name of the ship, painted in bright crimson that was turned by the moonlight into the colour of dried blood:

NEMESIS

Behind me, I could hear Mr Ambrose suck in a sudden breath. Instinctively, I tried to turn, but hard arms grabbed me from behind.

‘Keep going!’ Mr Ambrose hissed. ‘They may be watching us from the ship, even if we cannot see them. Just keep going.’

‘But… you know that ship’s name. I know you do. What is the matter? What is so special about it?’

‘Keep going, I said! Or do you want us both to lose our heads tonight? Yes, I know the ship. Or at least, I have heard reports of it. If it is the one I think it is, it’s the most modern and devastating warship of the world.’

I stared at the slender, black silhouette of the two-master with mingled fear and incredulity. This? The most devastating warship of the world? I didn’t know much about ships, but most of the Royal Navy ships I had seen entering and leaving the port were much larger than this thing, with a great many more cannons and masts.

He has to be joking.

Then, my eyes fell once more on the threatening, black hull, and I remembered that Mr Ambrose did not ever joke.

‘Why?’ I asked quietly. ‘What makes it so dangerous?’

‘It is the first warship made entirely out of steel. Where other ships shatter and crumble under cannon-fire, this thing will simply sail on. It’s Lord Dalgliesh’s latest contribution to our great British Empire. The flagship of his fleet. Everybody was so pleased when he announced the project. What a great triumph for Britain’s naval superiority, et cetera. The Queen congratulated him.’