‘He thinks something’s gone wrong in Copenhagen. He hasn’t heard from Agent Osric for over a fortnight and his messages aren’t being collected. He sent another courier in at the weekend to retrieve the messages; didn’t want to risk anything. It’s most uncharacteristic of Osric: no warning signs at any of the dead letter boxes, nothing. As far as he can tell, she’s disappeared. He fears she’s been arrested by the Gestapo. The chap’s only a courier; George doesn’t feel he’s up to looking into it further.’

‘Oh dear. Perhaps a splash more sherry, Tom. Are you sure you won’t join me?’

‘Maybe a small one then, Roly. I’m afraid it gets worse. George has copies of Politken sent over to Stockholm; it’s one of the more reliable Danish papers. They carried a brief obituary last Thursday for Otto Knudsen: Agent Horatio. According to Politken, he died in police custody.’

There was silence in the room as Pearson sipped his sherry, his hands trembling slightly as he did so. ‘I don’t know, Tom, sometimes I worry we take these agents too much for granted, asking them to do things we know could result in their deaths. The poor woman. One shudders to think what has happened to her.’

It was a Saturday in the middle of February before Prince – now Pierre Breton – managed to get on a work detail to the beach near Zempin where his dead letter box was. There were three groups of prisoners that day: Ukrainians, Poles and French, and the latter just had the one guard, who as soon as they arrived went to join his comrades for a cigarette. Prince had come to realise that because there was so much security around the camp and on the island, the guards felt able to relax a bit in some of the areas where the men were put to work. It wasn’t as if they could escape anywhere.

While he had the chance, he hurried to the white-painted wooden post with the life belt attached to it. The short walk was up a steep incline, and he quickly found himself out of breath. He was constantly shocked at how easily exhausted he was now, sapped of energy, his body persistently cold, often wet and desperate for food. He used his boot to loosen the shale and sure enough there was a black waterproof pouch. He slipped it down the front of his trousers. He would read the contents later.

He lay on his bunk that night, staring up at the rotting board above him and unable to sleep. He’d read Sophia’s message a dozen times, memorised it and destroyed it. Now he was going over what it said again and again in his mind. It was hardly ambiguous.