‘I’m sorry to involve you, Margrethe, but the person I’m looking for was supposed to be on direct Deutsche Lufthansa flights to and from Berlin, but I can’t find his name anywhere.’

Margrethe leaned across, flicking the pages of the ledger. ‘Here, there is another direct Deutsche Lufthansa flight, but it shows as the Oslo service. It leaves Oslo at 14.55, lands here at 16.44, then takes off again for Berlin at 17.25, landing there at… here… 19.25. Same with the return: it leaves Berlin at 8.40 in the morning, lands here two hours later and forty minutes after that flies on to Oslo. A lot of people prefer this flight.’

And sure enough, on Monday 3 August, an Otto Knudsen was on the Oslo/Copenhagen flight to Berlin, returning from the German capital that Friday on the Copenhagen/Oslo flight. Even more helpfully, the ledger also contained his legitimationskort number.

Now she’d established that Knudsen’s journey to Berlin was indeed as he’d described it, there was, as she’d told the Englishman, just one more check she needed to make.

Knudsen lived in an apartment in one of the elegant six-storey painted houses on the Nyhavn canal. The building was on the south side of the canal, on the block between Heibergsgade and the Nyhavnsbroen bridge. It wasn’t difficult for her to gain access to Knudsen’s top-floor apartment. It took her just a minute to pick the lock, and she allowed herself ten minutes to look around.

She wasn’t searching for anything in particular, but she’d developed a good sense for whether something wasn’t right. For a start, there were no obvious signs that this was where a German sympathiser might live. The bookshelf contained no right-wing literature; there was nothing on his desk that appeared suspicious. The apartment was clearly that of an affluent man: well-kept and clean, with good furniture. She checked the drawers in the bedroom: a few letters and papers, nothing unexpected. There were three large paintings in the lounge, modern interpretations of boats on the canal.

Her ten minutes were up. Her gut feeling was still that Knudsen was who he’d said he was. Nothing she’d seen in his home disabused her of that.

Agent Laertes could now approach him.

She returned to the apartment off Carstensgade around eight in the evening, entering it so silently, as always, that he was aware of her presence only when she appeared in the lounge. There were few pleasantries; she only wanted to know everything was in order. She was concerned with security: any strange noises outside the apartment, that kind of thing. Then it was down to business.