‘Her apartment was around the corner and over on Gereonswall.’ Scholz indicated the street that swept away from them.

‘Something doesn’t make sense …’ Fabel looked back in the direction of the city.

‘What?’ asked Scholz.

‘I’m convinced that the killer lies in wait for his victims. But the church is on the wrong side. She wouldn’t have passed by here.’

Scholz smiled grimly and shook his head. ‘She was with friends when she came home. They split up here and headed off. Even if she had come this way, the killer couldn’t have grabbed her. She was with witnesses.’

‘Then he must have either persuaded or forced her to come up here.’

‘Must have.’

‘That could mean that this specific church does have a significance. There was no sign of sexual contact?’ Fabel asked although he knew the answer.

‘None,’ answered Tansu. ‘No semen, no evidence of sexual assault.’

The four detectives stood looking at the ghost of a murder scene. The second they’d examined that day. Fabel was beginning to understand the dynamic of this small team: Scholz acted as if he wasn’t the boss, Kris and Tansu called him Benni and never Chef, but the truth was that he steered his team probably more strictly than Fabel did his. Kris was the apprentice: quietly gathering the gems of wisdom from Scholz’s feet. Tansu was strong-willed and intelligent, but still unsure of her feet and unwilling to challenge Scholz. It was clear that he had closed his mind to Tansu’s theory about the rape victim in ’ninety-nine. Fabel, on the other hand, could see her reasoning.

‘There’s something you’ve got to see.’ Scholz hunched up his shoulders against the cold and led Fabel towards the vast dark doors of St Ursula’s. Fabel followed him into the church, gazing up at the vaulted ceilings and the stained glass that burned dully against the winter light beyond.

‘Very nice.’

‘That’s not what I wanted to show you.’ Scholz guided Fabel to a vast reinforced door immediately to the right of the main entrance.

‘We’ll stay here,’ said Tansu. ‘It gives me the creeps down there.’

Fabel and Scholz went down stone steps into the crypt of the church.

‘This is open to the public during the day, but it’s monitored constantly by CCTV. And that massive door you saw is shut tight and time-locked at night.’

Fabel stopped in his tracks. The vaulted ceiling was whitewashed, with gilded details. Apart from that, it was as if the whole space had been lined with gold. But it was what the gold covered that fascinated Fabel.

‘The Golden Chamber …’ explained Scholz. ‘St Ursula’s is the second-oldest Romanesque church in Cologne. As you saw, the city has kind of encroached on its space, but there used to be an extensive graveyard outside dating back to Roman times.’