'Sarge? You hear me?'

'Yeah,' she said. 'I hear you.'

She picked up the hand. She cupped it gently, and slowly let herself sink to hover above the silt at the bottom of the harbour.

'Sarge?'

'Yeah, Dundas. Yeah. I'm with you.'

'Got anything?'

She swallowed. She turned the hand round so its fingers lay across her own. She should tell Dundas it was 'five bells'. A find. But she didn't. 'No,' she said, instead. 'Nothing yet. Not yet.'

'What's happening?'

'Nothing. I'm going to move along a bit here.

I'll let you know when I've got something.'

'OK.'

She dug one arm into the muck at the bottom and forced herself to think clearly. First she pulled gently at the lifeline, dragging it down, feeling for the next three-metre tag. On the surface it would appear to be paying out naturally — it would look as if she was sculling along the bottom. When she got to the tag she sandwiched the line between her knees to keep up the pressure and lay down in the silt the way she taught the team to rest if they got a CO₂ overload, face down so the mask didn't lift, knees lightly in the sludge. The hand she held close to her forehead, as if she was praying. In her coms helmet there was silence, just a hiss of static. Now she'd got to the target she had time. She unplugged the mic from her mask, took a second to close her eyes and check her balance. She focused on a red spot in her mind's eye, watched it, waited for it to dance. But it didn't. Stayed steady. She kept herself very, very still, waiting, as she always did, for something to come to her.

'Mum?' she whispered, hating the way her voice sounded so hopeful, so hissy in the helmet. 'Mum?'

She waited. Nothing. As it always was. She concentrated hard, pressing lightly on the bones of the hand, making this stranger's piece of flesh seem half familiar.

'Mum?'