The witch’s cauldron drilled deep into the rock, so deep you could not see the bottom, only a black, churning hole where the water was sucked down as the sea went out. Round and round the water spun, draining away to reveal a narrow shelf encrusted with barnacles and seaweed. Then, quite suddenly, up the water gushed again, pouring over the side like an over-boiling pot.
‘I dare you to jump in!’ Thomas said. He was nicknamed Thomas the Tank because he was strong and square and always charged straight ahead. Although he was a year younger than Ben, he was just as tall and twice as wide. His sister Meg was called the Little Princess, while Gus, the youngest, was called Super-Gus because he liked to dress up as a superhero – if he wore any clothes at all.
‘No way,’ Ben said, looking down into the dark, fathomless hole.
‘Don’t you dare!’ Mum called. ‘Else we’ll go straight home!’
‘OK, OK,’ Thomas said, and rolled his eyes at Ben.
They clambered back down to the beach, where Meg and Tim were building a giant sandcastle. The four cousins dug moats and channels, erected high walls and towers, excavated dungeons, and made drawbridges out of twigs and flags out of seaweed. It took much longer than it should have because Gus and Ella thought it was great fun to jump into the castle and smash it down. Eventually, Aunty Vic and Mum took Gus and Ella down to the lagoon to hunt for crabs so the cousins could build in peace.
Ben sat back on his heels to admire the castle, then looked round for Jessie. She was down at the water’s edge, growling and trying to bite the little waves that came scampering in and out. The tide had crept in while they were busy, and the little pools where they had sat and splashed were now all swallowed up into one big pool where the waves raced round and round in circles like Jessie chasing her tail. Beyond the ring of barnacle-encrusted rocks, the sea roared and pounced and threw up great white spumes of spray.
And lying on the tall pinnacle of Lookout Rock, peering down at them, were two children.
All Ben could see were their faces, pale and wedge-shaped, and half covered by long, wet, bedraggled hair. Curious, Ben stood up, still staring at them, and at once the children slithered away out of sight.
‘We’re being spied on!’ Ben cried. ‘Come on!’
The four children raced across the sand and clambered up the steep rock. There was nobody there.
‘But where could they have gone?’ Ben wondered. ‘They can’t have dived into the witch’s cauldron or jumped down into the sea, it’s much too dangerous.’
‘You must’ve imagined them,’ Thomas said.
‘No, I saw them, clear as anything,’ Ben said. He stood on the very edge of Lookout Rock, staring down at the heaving ocean. A flash of silver caught the corner of his eye, like the flick of a tail through the waves. ‘Look, there!’
‘What is it?’ asked Meg.
‘Some kind of big fish? I don’t know.’
Someone giggled. All four children spun round. They looked high, they looked low, they looked far, they looked near, but they could see no-one. Then the giggle came again, quickly muffled as if by a hand.
‘Look, down there!’ Tim called. ‘In the witch’s cauldron. It’s a girl!’
Staring up at them from the round, bubbling witch’s cauldron was a young girl with long, sleek, dark hair and laughing eyes. As soon as she saw that the four children had spotted her, she flipped and dived under the water, disappearing into the foaming maelstrom of the blowhole. Just as Meg cried out in dismay, a sinuous, frilled tail broke through the bubbles with a resounding SPLASH!
Then the girl with the tail like a fish was gone.
