Cat wanted to run to Shane, but she struggled to keep hold of the bottle as the essence of the ancient creature poured into it. Finally, when the waters calmed again, Cat capped the bottle and closed it as tightly as she could. She looked around for Shane, panicking that it had all been for nothing, before spotting his prone form lying in the mud by the water’s edge. She hurried over and dropped to her knees beside him.

‘Shane?’ she said, ‘It’s me! Are you OK?’

When there was no response, Cat began to worry.

What if he needs CPR? I don’t know how to give CPR!

Then, with an almighty gasp and a heave, Shane flipped to his side and vomited up several litres of dirty pond water.

‘Eugh!’ said Cat, leaping back. She might have been wet and dirty herself, but she drew the line at getting sick on her.

‘What happened?’ said Shane, looking up at Cat with bleary eyes. ‘Why am I wet?’

‘You’re alive!’ Cat said, beaming at him.

‘Well, yeah obviously … wait, was there a chance I wouldn’t be?’

Cat held out her hand and pulled him to his feet. ‘I’ll explain as we go,’ she said.

She had just managed to get Shane upright when a soft tug at her elbow caused her to turn around. It was the ghost-girl. She was standing at the head of a veritable army of silvery figures, some more distinct than others. Two hundred years the Merrow said she had been there. Some of those children would have been trapped down there with her for several lifetimes. The thought made Cat shudder.

‘You saved us,’ said the ghost-girl, and Cat could have sworn that, if it were possible, her eyes had filled with tears.

‘Oh, um. I suppose I did, yeah.’

‘You didn’t have to.’

‘Yes,’ Cat said. ‘I did.’

The ghost-girl laughed and for a second Cat could almost imagine what she had looked like when she was alive.

‘I have something for you,’ she said, almost shyly.

With some effort, she held out her hand. In her outstretched palm was a smooth circular stone with a small hole in the centre that seemed to hum with power. Cat reached out and took the stone, gasping as her fingers brushed against the ghost-girl’s hand. Even that brief touch felt like plunging her hand into a bucket of ice.

‘It’s called a hag stone,’ said the ghost-girl. ‘My mam told me they were lucky. I hope it brings you some good fortune tonight.’

Cat examined the stone before slipping it into her pocket. There was something familiar about the it and she made a mental note to check the Book of Secrets as soon as possible.

‘Thank you,’ Cat said. ‘I’ll take good care of it.’

‘We need to move on soon,’ said the ghost-girl. ‘But I think we can stay a while longer, at least until dawn. Should you need us …’

Cat waved her away. ‘Thanks, but you’ve already done enough.’