‘Fine, yes, don’t make me screw it up, Mackenzie.’ She stepped back to the lab. ‘Okay, after that, you filter out the phosphorus and add a lye solution to neutralise the rest of the acid.’ Now she paused. ‘Here comes the gamble. The science is sound, it should work.’

‘What should work?’ said Mackenzie. ‘Shelby, don’t take chances . . .’

‘I have something that should bind to the ice without affecting . . .’ She poured a few drops of golden liquid into the mix from a glittering, unmarked bottle. ‘Then we drain the liquid meth out.’ She poured it into another beaker. ‘Now we bubble hydrogen-chloride gas through it, which will turn it into crystal – crystalline hydrochloride salt.’

Once it was ready, she poured it through a filter cloth. ‘Now we leave it on here until it dries.’

The crystal was a rich golden yellow, transparent as stained glass.

‘You turned it gold?’ Mackenzie was on the edge of a pit of despair. He couldn’t believe he’d let her blow their one chance at this. ‘Shelby, the purest ice is translucent. No one is gonna buy this!’

‘I know what I’m doing,’ she snapped, wiping sweat off her forehead. She waved the glittering bottle. ‘This is what’s going to distinguish us from the competition. I bet no one else is cooking golden ice.’

‘No one will buy it, either,’ said Mackenzie.

‘They will once they try it.’

The sun shone down on them as they sunbaked on the deck, waiting for the ice to set. Mackenzie was shirtless and Shelby had stripped down to her bra. He pointedly looked away, which made her give an earthy chuckle.

When the timer on her phone went off she busily pulled her shirt back on.

‘Let’s go have a look, then.’

Mackenzie dressed and followed her back inside.

The crystals had dried and cracked. The shards looked like delicious toffee. Mackenzie’s mouth watered. He hadn’t been this close to ice for ages . . .

Fight it, said one voice in his mind.

But another, dangerously rational-sounding voice betrayed him . . .

‘I’ll have to try it,’ said Mackenzie.

‘Don’t be stupid,’ said Shelby.

‘We can’t give Blackbeard ice that’s bad. It’ll ruin everything.’

He’d already begun rummaging in the kitchen cupboards. He soon found what he was looking for: a wineglass with a long bowl and a narrow rim.

‘I don’t think so,’ said Shelby, holding out a shaking hand. ‘My creation, I’ll be the one to trial it.’

‘Not a chance. I won’t let you expose yourself to that. We need your brain more than we need mine.’

‘And I’ve done the research, Mack. You’ve had psychosis before. If you smoke ice, you could easily lose your mind again. My brain is fresh as a daisy.’