‘As you can see, we’ve got rather a lot of steam from the boiler at the moment,’ Bonhoeffer shouted. As the prow narrowed, the walls formed an acute angle, like in an attic, and there were no closed windows, just open holes. Given how close they were to the sea here, and that Sultan had now reached its top speed, you had to shout at the top of your voice to be heard over the noise the ship made as it followed its course. Martin felt as if he were inside a steel kettle being bombarded from outside by a water cannon.

‘Normally there’s no access here when we’re out at sea,’ the captain said. He went on to explain to Martin that last year a drunken Canadian had managed to climb into the anchor room and let the chains down from the capstan. The anchor had damaged the propeller, gouged a hole in the ship and rendered it completely unsteerable. At the time the Sultan had just filled up with three and a half million euros worth of fuel. What would have happened had the anchor caused a leak in the fuel tank didn’t bear thinking about.

Today the pisshead was in jail for dangerous infringement of ship security, and since then the doors to the anchor room could only be opened when the liner came in and out of port.

‘I had to get my chief engineer to remove the electronic security lock,’ Bonhoeffer concluded. ‘It couldn’t be done any faster.’

Martin looked around. They’d entered the room on the port side. Turbine-like constructions, possibly generators, covered an area which would have easily accommodated twenty parking spaces. He saw a metal cage, which was used to store the mooring ropes, and several cupboards that looked like fuse boxes with warning stickers indicating high voltage.

And then, of course, there was the chain. Painted black and huge. Viewed up close it looked like something an enormous macho giant might wear across his chest. Martin could have easily slipped his forearm through the links. And he’d have needed a dozen arms to lift just one of them. ‘Seventy tonnes,’ Bonhoeffer said, knocking on the metal monster as if they were on a sightseeing tour.

The chain was coiled on a huge, pistachio-coloured metal reel – the chain winch, reminiscent of an outsized train wheel – and then ran down via a slightly smaller winch into a chimney-sized shaft, which at the moment was blocked by the anchor set firmly into the hull.

Anouk’s drawing flashed through Martin’s mind.

Through small gaps he could see the choppy water of the Atlantic.

‘The anchor itself weighs ten tonnes,’ the captain said, going further into the room.