‘When you have had time to absorb everything, I hope you’ll come to understand that I am on your side, that I am doing this to protect you.’

‘Oh for God’s sake, Tom, spit it out.’

He looked at her and remembered how happy she had seemed at the pool, so attentive towards François, so relaxed and unguarded. He wished he wasn’t about to take it all away.

‘Your trip to France raised some alarm bells.’

‘I’m sorry?’

‘Please.’ Kell lifted a hand to indicate that he would explain everything, but in his own time. ‘Simon and George got nervous. They couldn’t work out why you had taken off at such short notice. So they had you watched in Nice.’

‘How do you know this?’

He marvelled at the nonchalance of the question, as though Amelia was merely enquiring after a point of detail. In all probability she was already several stages ahead of him, seeing the problem in seven dimensions, anticipating everything that Kell was about to say and calculating its implications.

‘Because when you disappeared, Jimmy Marquand hired me to come and look for you.’

Kell watched Amelia’s face. ‘I see.’

‘Look.’ He had sat at the edge of a large table, but stood again now and paced towards the sofa. ‘Long story short, I got the keys to your hire car from the safe in your room at the Gillespie …’

‘Jesus.’ That caught her out. Amelia stared at the floor. Kell found himself saying: ‘I’m sorry’ and felt a fool for doing so.

‘I got hold of your BlackBerry, traced some calls …’

‘… and followed me to Tunis. Yes, I understand.’ There was now a degree of hostility in her voice.

‘The man you were with in Tunis,’ he said, no longer wishing to prolong Amelia’s suffering, ‘he is not who you think he is.’

She looked up. It was as though he had stepped on her soul. ‘And who do I think he is, Tom?’

‘He is not your son.’

Four years earlier, Kell had sat with Amelia Levene in a control room in Helmand province when news came in that two SIS officers and five of their American colleagues had been killed by a suicide bomber in Najaf. One man in the room, still a senior figure in SIS, had broken down in tears. Kell himself had accompanied his opposite number in the CIA outside and comforted her for fifteen minutes in a passageway that buzzed with oblivious Marines. Only Amelia had remained unaffected. This was the price of war, she would later explain. Almost alone among her colleagues, she had been full-square behind the invasion of Iraq and incensed by the bien-pensant Left, on both sides of the Atlantic, who had seemed happy to leave Iraq in the hands of a genocidal maniac. Amelia was a realist. She didn’t live in a black-and-white world of simple rights and obvious wrongs. She knew that bad things happened to good people and that all you could do was stick to your principles.

So it did not surprise Kell when she looked at him with an almost stubborn indifference and said: ‘Is that so?’

He knew how she worked. She would do anything to maintain her dignity in front of him.

‘I tracked down his closest friend in Paris,’ Kell said. ‘A man named Christophe Delestre. There were two funerals. Philippe and Jeannine Malot were cremated on July twenty-second at Père Lachaise. That service has now been wiped from the public record, almost certainly by elements in the DGSE. You attended a similarly intimate funeral on July twenty-sixth at a crematorium in the Fourteenth. Is that correct?’

Amelia nodded.

‘Did this man make the eulogy?’

He passed a photograph of Delestre to Amelia, taken on his mobile phone in Montmartre. She looked at the screen.

‘This is Delestre?’

‘Yes.’

‘I’ve never seen him before. There was no eulogy. Just a Bible reading, some …’ Her voice trailed off as she realized what had happened. ‘The funeral was a set-up.’

Kell nodded. He did not like to see Amelia suffering, but had no choice but to press on. ‘At the end of my meeting with Delestre and his wife, I showed them a photograph of François lying beside the pool at the Valencia Carthage. They didn’t recognize him. He said the two men were similar in build, in colouring, but that was all. He had never seen this man before in his life.’

Amelia stood up from the sofa, like a physical rejection of what Kell was telling her. She went into the kitchen and poured herself some water. She came back holding two plastic cups, one of which she handed to Kell. It did not seem as though she was ready to speak, so Kell assembled the final points of his theory and put them as delicately as he could.

‘It seems likely that Paris found out about your son at some point in the last few years, arranged for Philippe and Jeannine to be murdered, then put you alongside an agent whom you assumed, because you had no reason to doubt him, was François.’

Amelia took a sip of the water. There was an obvious question and it was as though she could not bear to ask it.

‘What about François?’ she said. ‘What about my son?’

Kell wanted to come forward and to hold her. All through their long association he had been careful never to allow his affection for Amelia to cloud their professional relationship. He needed all of that discipline now. ‘Nobody knows what’s happened to him. Delestre has received emails and text messages which indicate that François may still be alive. There’s a strong chance that he’s being held captive by the DGSE, possibly at a safe house in the Languedoc …’

Suddenly, from the opposite end of the office, came the ping of a lift and the distant sound of doors sliding open. Kell looked up as a middle-aged South American man emerged on to the landing, trailing a vacuum cleaner. Walking towards him across the open-plan office, Kell saw that the man had a set of keys in his hand and was preparing to unlock the door.

‘What do you want?’ he shouted.

‘It’s just the cleaner,’ Amelia muttered.

Through the glass, the man lazily waved a hand and indicated that he would return when the office was empty. Kell walked back to the sofa.

‘Held captive?’ Amelia asked. Kell could see how hard she was working to mask her despair.

‘It makes the most sense,’ he replied, but found that he could not elaborate. His mind was momentarily blank. He had no clue as to François’ whereabouts, save for the fact that the man impersonating him had been dropped off by a Marseille cab driver near a village south of Castelnaudary. Amelia pulled on her shoes, covering her painted toes.

‘It’s certainly an interesting theory,’ she said. Kell still did not know what to say or do. Bending forward, Amelia flicked a speck of dust from her tights. ‘But it rather begs a question, don’t you think?’

‘Several,’ Kell replied, and wondered if she was preparing to leave.

‘Such as why?’

‘Why you?’ he said. ‘Or why kidnap François?’

Amelia produced a look of quick contempt. ‘No, not that.’ Kell felt momentarily insulted. ‘I mean, why stage such an operation? Why murder two innocent civilians? God knows the Service Action has carried out quiet assassinations on foreign soil, but what did Philippe and Jeannine ever do to anyone? Why would the DGSE take another risk on the scale of Rainbow Warrior? To humiliate me?’

‘You ever hear of a DGSE officer using the legend Benedict Voltaire?’ Kell asked.

Amelia shook her head.

‘Tall, mid-fifties, smokes filterless cigarettes. A lot of them. Sarcastic, a bit macho.’

‘You could be describing every middle-aged Frenchman I’ve ever met.’

Kell was too tense to laugh. ‘Dyed black hair,’ he said. ‘His real name may be Luc.’

Amelia flinched. ‘Luc?’

Kell moved a step towards her. ‘You think you might know him?’

But Amelia seemed to back away from the coincidence, suspicious of any probable link. ‘Must be a hundred Lucs in the Service. In the run-up to Iraq, I became entangled with a man who roughly fits that description, but we shouldn’t jump to conclusions.’