‘What do you think happened?’ It was cold. A draught blew up the stairwell. He knew that the last thing she’d want would be sympathy.

‘She must have been killed not long after we came to see her.’ Vera was standing with her hands in her pockets. There wasn’t much room there and his elbow brushed against her arm.

‘A customer?’

‘She was dressed for work, but still wearing her knickers. No evidence that sex had taken place.’

He could tell that she’d already thought this through. ‘It could still have been a punter,’ he said. ‘We know that she wasn’t much good at risk assessment. She went off with that guy Jason, without knowing where he lived.’

‘The link with Margaret Krukowski is just a coincidence, do you think?’ Vera gave a sharp little smile. ‘That’s some elephant-sized coincidence.’

‘What then?’ He was losing patience. If Vera Stanhope had a theory, why didn’t she just tell him? Why play games?

‘Dee Robson knew something about Margaret’s killer,’ Vera said. ‘But she didn’t know that she knew. Otherwise she’d have told us when we saw her yesterday.’ There was a pause. ‘Or maybe she was smarter than anyone thought.’

‘Blackmail?’ Sometimes he knew the way her mind was working. ‘She kept the information secret so that she could make money from it.’

She gave a slow clap. ‘Well done, that boy.’

‘You think that she’d have been capable of that?’ He couldn’t see it. He didn’t think Dee had been bright enough to make the connections, and he’d been convinced by her performance the day before.

‘She was desperate,’ Vera said. ‘An alcoholic, living like this – there’d be an incentive to get money any way she could. Maybe Margaret said something to her when they last met. Something so obvious that you wouldn’t have had to be Einstein to work out who’d killed her.’

There were footsteps on the stairs and Billy Wainwright appeared. He looked grey and ill.

‘You okay, Billy?’ Joe disapproved of Billy’s lifestyle choices – the string of young lovers seemed undignified for someone of his position – but couldn’t help liking him.

‘A bit of a hangover. Nothing a good night’s sleep won’t cure.’ He was already in the scene suit and was putting on a mask, so the words were muffled.

‘I thought you were so busy with the crime scene in the Metro there’d be no time for partying.’ Vera’s words were sharp.

‘All work and no play . . .’ Joe could tell by his voice that he was grinning. ‘You could do with a bit of play yourself, Vera.’

‘Just go in there and do your work, Billy. Tell me who killed these women. Find some fibres or spit or fingerprints, and link the two investigations. That would be a good start.’