He focused on Klugmann’s face in the service photograph. It was a leaner face than the one that had been opposite him in the whitewashed interview room in the Davidwache station. It was a taut face, the skin pegged tightly to the heavy skull by guy-rope muscles and ligaments. It was the kind of face that told you that the unseen body to which it belonged was powerful and fit. The photograph wasn’t that old; Klugmann must have worked at making himself look that little bit run down for his undercover role.

What Fabel couldn’t fully understand was why a GSG9 agent was being used to go undercover. GSG9’s stealth was a tactical, operational tool, not an intelligence-gathering one. Fabel had no doubt that if Maria was convinced she had encountered Klugmann before at Weingarten then that’s exactly where she had seen him. And the two locations GSG9 used for training were Hangelar and Weingarten. There was no doubt, with so many special agencies involved, that whatever the focus of the operation, the objective was a major one. Volker was BND; Klugmann was GSG9. Fabel’s guess was that the dead girl, Tina Kramer, had really been BND too. Only the Polizei Hamburg itself seemed to have been excluded. And Fabel had no reason to doubt Van Heiden’s word that he knew nothing whatsoever about the operation. So why was the principal law-enforcement agency for Hamburg kept out of the loop?

There was a knock on Fabel’s door that was neither tentative nor assured. Volker stepped into Fabel’s office without waiting to be invited. Something had bulldozed across Volker’s face and swept with it any vestige of geniality. There was no hostility in Volker’s expression, neither was there any other recognisable emotion. This, realised Fabel, was Volker behind the affable mask. The dark eyes were empty and the mouth a straight, determined line. Volker had a thick green file tucked under one arm. Fabel gestured towards a chair.

‘What is it you want to know, Fabel? I’ll tell you what I can.’

When Fabel spoke, there was a steel cord in his voice. ‘No, Volker … you won’t just tell me what you can …’ Fabel beckoned to Werner, who came in, closed the door very deliberately behind him and leaned his heavy frame against it, folding his meaty arms across his chest. ‘You’ll tell me everything I want to know. And if you don’t, I promise you I will put you in a cell, charge you with obstructing a murder inquiry and leak the story to the press before your pals in Pullach can weasel you out of it.’

‘We’ve had a very good reason for playing this close to the chest, Fabel. We are still on the same side, you know.’ Volker’s face remained expressionless.

‘Are we? I’m trying to solve a series of vicious murders and you have been withholding information – key information – from me. I have had people wasting their time all over Hamburg trying to find out who the second victim was while you saunter in and out of the Präsidium with her identity in your pocket. In the meantime a third victim is killed. You fuck about playing secret agents and some poor woman pays with her life.’