In a sudden decisive movement, Tom climbed the steps and pressed his finger on the top floor flat’s bell. They held their breath. When there was no response, his hand moved to hover over the next one but before he could press it, the intercom clicked and crackled. ‘Who the fuck is this?’ a deep male voice growled.

‘Sorry, mate,’ Tom said, ‘I think I—’

‘Fuck off or I’ll call the police.’ There was a click then the intercom was silent once more.

‘Let me try.’ Clara pressed the next bell and they all waited. No answer. Then the one below. A crackle, then a sleepy, female voice with a Jamaican accent, ‘Yeah, hello?’

‘I’m sorry,’ Clara said, ‘But I’m afraid I’ve locked myself out, I live on the ground floor and I forgot my key. I’m really sorry, could you—’

The woman kissed her teeth. ‘Fuck’s sake.’ The door buzzed. They were in.

In the communal hallway they looked at each other with wide eyes. It was horrible; the carpet threadbare and stained, piles of takeaway delivery leaflets and unclaimed post littering the floor, the walls dirty and scrawled with graffiti, mould creeping over the dirty paintwork, a musty, sour smell in the air. And at the far end a filthy, battered-looking door. ‘That must be it,’ Tom whispered.

Clara turned to the others. She swallowed hard. ‘So we do this like we planned?’ she said. ‘You all need to stand back out of sight.’ Wordlessly they nodded, flattening themselves against the wall.

Fear dragged its fingernails down Clara’s spine as she approached the door and knocked. Seconds dripped by in absolute silence. She brought her fist up and knocked again, harder this time. She strained her ears to listen and thought she heard the faintest sound from within. ‘Hannah,’ she said, her voice emerging from her lips as a croak. She cleared her throat and forced herself to speak louder. ‘Hannah, it’s Clara.’

There was silence, but Clara felt her there, listening. Her voice shook as she said, ‘I’m alone. But I have my phone ready to call the police. I just want to talk to you.’

And then Hannah’s voice loud through the door: ‘Leave now, or I’ll kill him. Get the fuck away from here.’

Clara shrank back, her heart pounding. When they had discussed this in Mac’s kitchen, gone over and over how they could get Hannah to open her door, the plan they’d come up with had seemed feasible. But here, now, with Hannah only inches away, it felt absurd, impossible, like using a penknife to fell a tree. And if it didn’t work, what then? What would happen to Luke? They must have been crazy to take such a risk. She took a deep breath. ‘Hannah,’ she said. ‘I know everything. I know what happened to your mother. I know how she really died.’