Georgie did as she was told, although it felt as though her legs might buckle at any moment. They looked pathetic, ill equipped to support her body.

‘Just concentrate on my voice,’ Li told her. There was something reassuring about the way she was speaking; a calmness Georgie hadn’t heard before. Whatever it was, she was grateful for it. It might keep her alive.

‘Another few steps,’ Li said, moving to the other side to check the pool. Georgie shuffled forward, it was agonising progress but every small step was a step closer to safety and with Li surveying the water she might be able to react if . . .

‘There!’ Li was pointing to something in the far corner, behind her. The lionfish must have surfaced, although Georgie couldn’t see it but there was no time to think about it: if the fish was behind her then she could . . .

‘Run!’ Li shouted.

Georgie ran, thrusting herself through the water, sending spray everywhere, the stone floor cutting into her feet and sending shock waves of pain up her legs but she didn’t care – she was almost at the end, almost within reach of Li’s outstretched hand – when she stepped on something. Trying to avoid penetration, her leg collapsed underneath her. Was that it? Georgie felt herself falling forward into the water, head first, her arms flailing uselessly in all directions. She wasn’t going to make it. She was going to die in this basement like Alexia Elias. Fox was going to win.

She tasted the vile water in her mouth, grit and mud filled her stomach as her hands felt the pool bed and jagged edges of the stonework. She couldn’t breathe, couldn’t inhale. Panic seized her. Her mind went blank.

Just as she thought she might pass out something else happened. There were hands under her arms, pulling at her. There was a commotion in the water, someone shouting and then the sensation of air as her head lifted free. Li was in the water and had her round the torso. She hauled Georgie up the steps, throwing her like a bale of hay onto the side before collapsing next to her.

Starved of oxygen, Georgie heaved and spewed muddy water and vomit out in front of her. Every inch of her body hurt – her lungs felt like they were on fire.

But the relief was intoxicating. She was alive.

Dripping wet, Li sat up, rolled over and slung a hand over Georgie, laughing. ‘Fucking hell,’ she gasped. ‘I thought you were supposed to be just having a look around.’

‘Sorry,’ Georgie said breathlessly, although it hurt to talk. ‘I don’t know what happened at the end.’

‘Think you blacked out.’

‘Thought I’d stepped on it. Felt like everything had caved in on me. Must have been a blasted rock or something.’

‘You panicked. No shame in that.’

‘Thank you. Thank God you saw the fish behind me.’