‘We left three dead behind us in Ukraine,’ said Olga Sarapenko. ‘What you mean to us is an extra pair of eyes. And an extra gun if we need it.’

‘But your true value to us, Maria,’ said Buslenko, ‘is the connection you offer. The potential access to intelligence that we can’t get at ourselves. There’s a dossier on Vitrenko. In fact there are two, but one of them, the more comprehensive one, is held by your Federal Crime Bureau on a secure computer. Hard copies are on very restricted circulation. The Federal Crime Bureau task force dedicated to Vitrenko obviously has access to inside information. We only had sight of the Ukrainian version which misses out key intelligence.’

‘Vasyl Vitrenko is obsessive about security.’ Olga Sarapenko took over. ‘He is driven mad by the idea that he can’t get at the dossier. He suspects that the informer is on Molokov’s side of the operation, maybe even Molokov himself. But he can’t prove it. We want you to try to get us a copy of the Vitrenko Dossier. The full one. If we can identify the informer, we can pressure him into setting Vitrenko up. It gives us someone on the inside whose survival would depend on us taking Vitrenko out of the picture.’

‘But I don’t have access to the Vitrenko Dossier. In fact I’m probably the last person they’d allow to see it.’

‘But you have access codes and passwords for the BKA computer system,’ said Buslenko. ‘That would be a starting point. It’s not practical to think that we can carry out a complex mission like this in just a few days. It could be that the best thing for you to do is to go back to Hamburg in a few weeks and ideally resume your duties with the Murder Commission. The information you can obtain for us is of much more value to us than your presence here,’ Buslenko explained.

‘I’m here to see this through. To see Vitrenko get what he deserves,’ Maria said defiantly. She was willing to do almost anything to bring down Vitrenko, but Buslenko was asking her to access government files on behalf of a foreign military unit operating illegally in the Federal Republic. It would be a betrayal of her office. It would probably be espionage.

‘I understand your hunger for revenge,’ Buslenko explained. ‘But this is not a Hollywood western. Your value to us is to pass on to us everything that the German authorities know about Vitrenko’s operation. I’m sure you’ll find a way,’ Buslenko said, not unkindly. ‘In the meantime, you may stay here with us and help us set up our surveillance of Molokov.’

Maria took her shifts watching the monitors, logging the activities: who visited the Molokov villa, when they arrived, when they left, the licence numbers of the cars that came and went. Always waiting for the arrival of anyone who could have been Vitrenko. Although she refused to supply the Ukrainians with the access codes they needed, she did share what intelligence she had been able to gather. She felt that this, in some way, could be regarded as the legitimate exchange of information between law-enforcement agencies.