‘Hello? Hello?’ I repeated irritably. ‘Is anyone there?’

Just one long, slow breath – and then the line went dead.

‘For God’s sake.’ I considered the phone in my hand for a second, then I rang Alex’s number. It went straight to voicemail. I slammed the mobile down on the side of the sink, and stood for a minute. Then I fished out my eyeliner. ‘Bloody bollocks to you, too.’

The frosted window rattled suddenly; one of the cubicle doors banged. I jumped, drawing a great kohl tick across my cheek. Immediately tense, I peered round. I was sure I’d been the last one in the office.

‘Hello?’ I hated the fact my voice wavered as I spoke.

I thought I heard the shuffle of feet. A clammy sweat broke out on my top lip. I took a deep breath and crept down the row of cubicles to the one nearest the exit. It was shut.

‘Is anyone there?’

I stared at it and then quickly pushed the door: it swung open and smacked hard against the wall. The cubicle was empty. Nervously I laughed at my overactive imagination, but I struggled into the dress as fast as I could, not caring that I couldn’t reach the zip myself. I wanted to get out of there. As I walked into the corridor, one of the fire-exit doors swung shut.

I took a deep breath. I had to retrieve my stuff from my office, which was in darkness now as I hurried across, just the ghostly flicker of light from the computer’s screensaver. As I grabbed my bag, I heard another noise.

‘Who’s there?’ I swung round, my voice sharp with fear.

Silence fell again across the darkened room. Perhaps it was one of the cleaners. Perhaps I’d imagined it.

I hurried towards the lift now – and then I heard a cough. A definite cough. I froze for a second behind the central pillar, my heart pounding. Silence fell again.

I shook my head. I was being silly. Except, if I was being silly, why had no one answered when I’d called?

And then a low voice, sullen, wheedling, slunk out across the darkness. Peering round the pillar, I noticed the crack of light under Charlie’s door. I took a deep breath and crept nearer. I could hear the mutter more clearly: a lone voice. It wasn’t Charlie – that much I knew for sure. Flattened against the wall outside the door, which was slightly ajar, I realised someone was using his phone.

‘But what’s in it for me? I need some sort of assurance,’ I heard. A pause. Then –

‘So if I do it, you’ll sort the …? Okay. And can you put that in writing?’ the voice said. Another pause. ‘No, I realise that.’