‘Sarge – that’s it. You’re over fifty. Can you hear me?’

‘Hey, Wellard,’ she whispered, looking up to where the bubbles had cleared now, dispersed into nothing but frosty jags of light. Now, suddenly, everything looked as it should. The water was empty. ‘Is there anyone else in here?’

‘Anyone else?’

‘Yeah,’ she hissed, not wanting to sound scared. She hoped he’d turned the comms panel down. Didn’t want her voice broadcast across the water to every person on the quarryside. ‘Is anyone swimming around in here with me? You’d have seen them getting in.’

There was a pause, a hesitation. Then the voice, a little cautious. ‘Boss? You know you’re well over, don’t you? Maybe it’s time to put the standby in.’

Narcosis, he meant. At this depth it would be easy to succumb to the disorienting, poisonous effect that nitrogen could have at high pressure – her reactions and thoughts were as they’d be if she’d been in the pub all afternoon. A hallucination like this would be classic narcosis stuff. She stared up after the bubbles. It had been something dark, the size of a large turtle. But not with a shell. It was something smooth and hairless, with agility and strength. With the feet of a human being.

‘I’m not narked, Wellard, I swear. I’m fine. Just reassure me there’s no one else swimming around down here. That’s all.’

‘There’s no one in there. OK? And the standby’s getting ready now.’

‘No.’ Her umbilical had snagged on a ledge or a rock behind her. Irritably she lifted her shoulders, waved her right hand in the air to free it and felt it pop easily away from the rock or ledge, freeing her. ‘No need for anyone else. I’m nearly done here anyway.’

Wellard was right, of course. If this was narcosis she should get out. But she wanted one more minute to check that she’d searched everything, so, tilting herself back down, liking the way it eased the pressure on her mask, she pointed the torch ahead. There, about ten yards away, was the bottom of the wall, the edge of the quarry. She’d come as far as she could and there wasn’t any doubt about it: Lucy Mahoney wasn’t here. Good. She’d been right. She was going to enjoy surfacing and sending Pearce the message that he’d been wrong.