MacSwain reappeared with a dark-blue woollen cardigan which he draped across her shoulders.

‘We can go below if you’re too cold,’ he said. Anna shook her head. MacSwain smiled and handed her a plate of pâté, bread and herring salad. ‘Relax for a minute,’ he said, ‘there’s something I want you to see. I know you’re not a good sailor, Sara, so I promise to take it slow.’ He looked at Anna as if asking permission. Anna, like MacSwain, had not seen the MEK men move into position, but she guessed – she hoped – that they would be there by now, somewhere in the shadows. What she had to gamble on now was whether or not Paul had arranged cover for her should MacSwain take the boat out.

She resisted the temptation to search the pontoons for her support and kept her eyes resolutely focused on MacSwain.

‘Okay …’ she said and nodded; for her invisible audience, she added, ‘I think that’ll be fine.’

Paul Lindemann instructed the MEK not to intervene. Maria warned the Wasserschutzpolizei launch, which was now in direct radio contact with the team, that MacSwain was on the move.

MacSwain untethered the boat fore and aft and started the engine. Its deep, throaty rumble disturbed Anna, whose instincts told her that a lot of power and a great deal of speed lay in that rumble. MacSwain, as good as his word, took the boat out from its mooring slowly and gently. Anna noticed the relaxed, almost careless ease with which he manoeuvred the craft. She looked back at the receding mooring and just made out the merest hint of a shadow, moving low and fast towards the land end of the pontoons.

The Elbe stretched out before them, obsidian black and unfathomable, fringed on the far shore by the lights of the shipyard. MacSwain turned the boat so it was parallel to the shore and cut the engine. He hit a button on the console and Anna heard the rapid rattle of a heavy chain as the anchor slipped deep into the dark river. With the engine dead, Anna could hear the sounds of the water around them: she felt as if she were on the back of some vast, living thing whose breath and skin sleeked against the hull of the boat as its endless body rippled past beneath them. MacSwain killed the lights.

‘Isn’t it magnificent?’ he said, a gesture with his champagne flute sweeping along the distant shore.

In any other situation Anna would have been captivated by it: Hamburg glittered in the night and the Elbe held up a mirror to her beauty, animating the city’s sparkling reflection.

‘Beautiful …’ said Anna. ‘Really. I’m glad you brought me out here …’

‘I love this city,’ said MacSwain. ‘This is where I belong. This is where I will always want to be.’

‘But you’re British, didn’t you say? Don’t you miss …’ Anna tried to think of something British to miss – ‘the rain?’ she said with a laugh.