‘What about the Germans – the Gestapo?’

‘They fled: the general strike in Paris started on the fifteenth of August last year, and the uprising four days later, so they had plenty of opportunity to get out before von Choltitz surrendered the city on the twenty-fifth. Ten days seems to have been ample time for them to destroy any records they were leaving behind and bugger off, if you’ll excuse my language. I think your best chance is to find French citizens who worked for the Gestapo.’

‘Were there many of them?’

‘Enough. Does that surprise you?’

‘It does, actually,’ said Hanne. ‘In Copenhagen, it was almost entirely Germans who worked for the Gestapo.’

‘Well then, this isn’t Copenhagen, is it? Though many of the French citizens who were known to have worked for them and were arrested at the time have since been killed. Do you know where your Ferret worked when he was in Paris?’

‘For the Gestapo.’

‘Yes, yes, I’m aware of that, but they had two main offices here. Their headquarters was in rue des Saussaies in the 8th arrondissement, not far from our embassy actually and close to the Élysée Palace, but they also used 84 Avenue Foch, at the other end of the Champs-Élysées, which in many ways was better known – notorious may be a more accurate way of describing it. It was the SS headquarters, and the Gestapo had the sixth floor, I think. A lot of their interrogations were carried out there. If we had some idea of where the Ferret worked, it would help.’

Again they shook their heads.

‘And you say you have a description of him?’

Prince opened a small black notebook he had by his side. ‘Here we are… late twenties – this was at the end of 1943, remember – thick blonde hair and bright blue eyes.’

‘And that’s really the best you can do? Hardly narrows it down, does it! Never mind, I’ll come up with something. Meet me at noon tomorrow: there’s a bar on rue de Duras called Pierre et Fils; it’s near the embassy but also round the corner from rue des Saussaies. One question, though: there are two routes open to us, the official one and the unofficial one. Which one would you prefer?’

‘I’m not sure what you mean.’

‘The official one is rather like the épuration légale – it will mean putting in a request to the French authorities, asking them to start an investigation, et cetera. The unofficial one will be more like the épuration sauvage.’

‘Which one would you suggest?’

‘I think you know the answer to that.’

‘This is Marguerite.’

They were at the rear of the bar on rue de Duras, sitting in a high-backed banquette with what they assumed were fading ancestors of Pierre and his son staring down at them from the wall. The woman who’d come in with Wilson was perhaps in her mid-thirties; slightly younger than Prince and Hanne. There was some brief chat about the weather as they waited for the coffees to arrive, and Marguerite confirmed she was happy to talk in English. She spoke to the waiter, and soon afterwards, an opened bottle of cognac appeared on the table. She poured some into all their cups without asking.