Mark waited to see if she would simply accept his instructions, knowing she would. Anywhere else in the city, he would expect an argument, but he knew this area. The people who were from these parts were too scared to open their mouths or disobey.

That’s what he hoped. He couldn’t talk to DS Cavanagh himself – he didn’t want to give him the chance to talk him out of what he was going to do next.

She walked off down the stairs and Mark moved back into the bedroom, closing the door behind him. ‘Well?’

‘What?’

‘Have you contacted him?’

John was choking on his sobs now, but the laptop was open beside him. ‘I sent him a message, asking where he’s taken Holly. I thought that would be the same place as your girlfriend.’

‘Her name’s Natasha and you’d best hope nothing has happened to her.’

‘Right, right, okay, please…’

Mark let go of John’s jaw, wondering at what point he’d grabbed it. He was running on nothing but instinct now, making decisions before he’d had a chance to consider them. ‘What happens, after you send him a message? Will he respond?’

‘He should do. He always does. He talked me through everything that would happen, then shared it on the forum. He told us exactly what happened with the others.’

‘I don’t understand how he gets them to do the things,’ Mark said, motioning a whole lot of nothing with his hands. ‘We saw one of them on CCTV – she was doing something in a lift…’

‘Joanna,’ John cut in, then clamped a hand over his mouth. Mark was beginning to think John would be the worst person to turn to in a crisis. He crumpled under pressure far too easily.

‘Yes, that’s right,’ Mark replied, swiping a hand across his own face, the sound of rough stubble bristling into his ear. ‘If you just wanted them out of your life, if it was just about getting rid of them, then I don’t understand the rest of it. Why make them do all the rest? Why not just go after them elsewhere?’

‘Because it has to be that way,’ John said, as if he were explaining something which didn’t really need an explanation. As if it were normal. ‘The rest… it’s just for fun. To see if they can be made to do anything they’re asked to do. It’s proper punishment.’

Mark rolled his eyes, trying to keep his composure. He winced as he bit into his lip too hard. ‘I think it’s more about making them look disturbed. You see that video of Joanna, doing her lift thing, and it looks like bizarre behaviour. It’s designed to make people willing to accept she would commit suicide. It’s a way of whoever this guy is covering his tracks.’