‘You ought to know how the KGB operated in the old days,’ he said, peering into the dark water. ‘They used the secret service organizations of East European countries as their tools. In Bulgaria, the Darzavna Sigurnost specialized in “wet” operations – contract killings. Do you remember the Markov case? It took place some years ago, at the height of the Cold War. Before your time, perhaps.’ ‘Thank you, Georgi. But I’ve heard of the case. A Bulgarian defector, wasn’t he?’

‘Yes. And after he defected, he was assassinated. In daylight, in a London street. They say he was injected with the poison ricin from the tip of an umbrella. They also say it was the Bulgarian secret service who carried out the assassination. No one in Bulgaria would contradict that report.’

‘Yes, but even so –’

‘Another dissident was shot in the back with a poisoned bullet near the Arc de Triomphe in Paris. Ricin was used in that incident, too.’

‘But –’

Kotsev held up a hand. ‘Wait. There was the attempted assassination of Pope John Paul II in 1981. You remember? It was alleged that Darzavna Sigurnost recruited the hit men who carried out the shooting – two Turks. When one of them was captured by the Italians, he made allegations against our secret service. But he retracted them after a spell in the Rebibbia jail in Rome, where he was allegedly threatened by Bulgarian agents. Afterwards, he blamed the plot on the Vatican itself.’

‘Even so, Georgi –’

Kotsev laughed. ‘Yes, you’re right. Even so. Like you, Sergeant, I do not believe our beloved secret service was involved in the killing of Dimitar Iliev.’

‘Who was it, then? Simcho Nikolov?’

‘Well, these killings were probably carried out by a local person, a paid assassin. Someone like Simcho Nikolov, perhaps. But it’s possible they were ordered by a major Bulgarian crime boss, one of the remaining Mafia. A very powerful man, particularly now that some of his leading rivals have been . . . eliminated. A man with friends in high places.’

Fry fought a brief internal battle between her own ambition and what she knew to be the proper protocol. Finally, she sighed. ‘This is really a matter for Special Branch or MI5 – they’re our lead bodies for organized crime. You’re scheduled to meet with them tomorrow in Chesterfield for a briefing on the Zhivko brothers.’

‘The Zhivkos are not a loss,’ said Kotsev, with a faint air of disappointment.

They had arrived at the point where water poured over a weir and the river formed little wooded islands populated by sleeping birds. Even at this time of the evening there were people by the river, enjoying an oasis of peace under the shadow of St Mark’s Church. Kotsev paused again.

‘We have our tourist attractions in Pleven, also,’ he said, admiring the reflection of the illuminated church spire in the water.

‘Really?’