Peering in through the glass was a little girl no bigger than Emmy. Her face was pale. Her eyes were wide and round. Long red hair flowed to her waist and around a thin blue dres.

Emmy shook her head. It was impossible for the girl to be where she was, because the only thing outside the window was a raging sea crashing against the cliffs below the house. There was nothing for her to be standing on.

She opened her mouth to scream again but the little girl stopped her.

‘Oh, don’t do that,’ she said. ‘It’s not nice.’

‘It’s not nice seeing a ghost,’ Emmy said.

‘Who says I’m a ghost?’ the little girl demanded.

‘You’re standing on thin air outside my window above a stormy sea,’ Emmy said. ‘What else could you be except a ghost?’

‘Oh, don’t be so silly,’ said the girl, looking exasperated at such foolishness. ‘I’m a water sprite. You can call me Ariel. It’s one of my favourite names.’

The wind howled. The rain hammered down. Far below Emmy’s window, giant waves thundered against the rocks with such force the whole house trembled.

None of this made Ariel so much as blink. She didn’t even look wet.

‘What are you doing out there?’ Emmy asked. She wasn’t scared any more. But she was really puzzled.

‘Looking for you,’ Ariel said.

‘Me?’ Emmy said. ‘Why?’

‘Because I’ve come to show you.’

‘Show me what?’

Ariel pointed at the sea.

‘I’ve already seen it,’ Emmy said. ‘I see it every day.’

‘I know that,’ Ariel said, grabbing her wrist and pulling her right through the glass as though it didn’t exist. ‘But you haven’t seen it from where I’m taking you.’

The next thing she knew, Emmy and Ariel were flying downwards, straight into the teeth of the raging waves.