Quinn drops Archer at the station and tells her he needs to sort out some personal business with a leak in his flat and will be back shortly. Archer says goodbye and heads straight into the office.

Later that morning, Klara’s contact with Megan Burchill’s dating app owners pays off. They are cooperating and send across the transcripts of Megan’s conversations with four different men. Three of them are from way back, but one is recent and stands out from the others.

‘Max084. It’s him. It has to be,’ says Archer.

Klara scrolls through the conversation. ‘He sent a car to pick her up the same night she disappeared. He must have driven that car himself.’

‘He pretended to be someone he wasn’t.’

‘It’s called catfishing,’ Klara tells her.

As they are speaking, Quinn walks into the room. ‘Morning! Sorry that took longer than expected. What’s the scoop?’

‘He’s using apps and technology to find his victims,’ says Archer.

‘Billy Perrin, Noel Tipping and Stan Buxton had phones but they were basic old-school devices used for calls only,’ says Klara.

‘Was there anything on their phone records?’ asks Quinn.

‘A few calls in and out to unregistered phones within Central London. That was it.’

Archer folds her arms. ‘I think you’re onto something. The killer used an app to catfish Megan. Jackie Morris said Elaine’s mysterious man had given her a phone to contact him. The killer uses the World Wide Web to showcase his victims. He knows what he is doing, he is savvy with technology.’

‘Oh God,’ says Klara as she turns to a different monitor, ‘I think you’re right. Look at this picture. I came across it this morning when I searched through Elaine Kelly and her friend’s Facebook pages. This is a picture of Jackie, Elaine and Jordan taken at the Lumberyard Café where Chau worked. Jackie tagged Elaine in it but Elaine’s security settings are set to not accept tagged photos on her timeline from other people. That’s why we missed it the first time.’

Archer feels her spine go cold. ‘When was that picture taken?’

Klara brings up the date of the posting. ‘It’s the same morning that “The Forsaken” cabinets were revealed.’

Archer’s eyes widen. ‘I was in the Lumberyard Café that morning. Chau was there. Elaine was there. He was there. The bastard.’ She tries to think. ‘Who else was there?’ she says out loud. Her mind scrolls back to that morning. She went there for a tea before the start of her new job. She tries to pick out faces from the clientele in her memory, but the truth is she didn’t take much notice having been so anxious about her first day at Charing Cross.

‘Klara, can you look at finding the public CCTV for that morning?’

‘I’ll get on it straightaway.’