“There’s a knack to opening this chest,” said the shop owner. “The shabby old sailor showed me. First you have to twist the dolphin’s head that’s carved on the front.” As she turned her hand, a panel next to the dolphin’s head slid back, revealing a crystal shaped like a teardrop.

“Then you have to move the chest into the sunlight.”

Eddy and the Captain pushed the chest forward. As light hit the crystal teardrop, it began to glow pink, and a flap on the top of the chest suddenly flipped open. With a gentle whirring of clockwork and cogs, a tiny golden harp rose into view.

“Then you have to strum the harp.”

She ran her hand across the strings. The notes crept into the shop like an angel’s whisper, then swelled into a tune so beautiful it would have melted a wasp’s heart. The crystal filled even the gloomiest corner of the shop with its pink glow, and the chest itself seemed to throb with a mysterious energy. Eddy felt the music flowing through him, tingling from his toes to his nose.

“And then,” said the shop owner, “you do this.”

She drew back her foot and kicked the chest as hard as she could. The glow vanished, the music fell silent, the chest let out a loud groan, and a hidden drawer shot across the shop like a missile. It bounced off a wicker basket, smashed a chunk out of a vase, clanged into an old bucket, and flipped over in the air.

Something faded and dusty fell to the floor, and unrolled towards them. Its edges were tattered. It was streaked and stained. It had a compass drawn in one corner, and islands with jagged mountains and palm trees, and at its top the words A Treasure Map. It lay before them, full of excitement and creases and a smell like old cabbage.

“A real pirate treasure map!” shouted Eddy.

“Grungeybeard!” shouted the Captain.

“Excuse me, dearie,” said the shop owner, “but what is a grungeybeard?”

“Not you as well?” said the Captain. “Settle your bottoms and pin back your ears, and I will tell you a tale – a tale of greed and folly and cruelty and madness – for I will tell you The Tale of Grungeybeard the Pirate!”

“Could you do it without the funny voice, please?” asked Eddy.

“What funny voice?”

“That one – you’ve gone all strange and wobbly and old-fashioned.”

“Have I? Sorry. Ahem. I mean, sorry. Right then – he was a wild one, was Grungeybeard. The terror of the high seas – him and his ship The Primrose. And you’ve got to be a real terror to get away with calling your ship after something as weedy as that. He thought it were a laugh to see grown men tremble when they heard the name of a little flower. But that was Grungeybeard for you – the only thing sharper than his sense of humour was his cutlass.

“For five fearless years he robbed and looted, and gathered the greatest hoard of treasure that any pirate has ever seen. And he had a high old time. He loved his luxuries – fine wines, expensive chocolates, lobster and caviar for breakfast. And he loved being famous, too. He paid poets to write verses and spread the news of his latest daring deeds.

“But all that treasure started to weigh on his mind. And his mind couldn’t bear it. If anyone admired the gold buttons on his waistcoat, or the silver buckles on his shoes, or the diamonds he’d had set in his teeth, Grungeybeard thought they meant to steal them. If anyone shook him by the hand, Grungeybeard would count the ruby rings on his fingers afterwards to check they were still all there. And then he’d count his fingers, to be doubly sure.

“So he decided to take all his most valuable treasure, and bury it in a secret place where no one would be able to find it. He loaded up a great oak chest – they do say that there were pearls as big as conkers, diamonds as big as gulls’ eggs, and emeralds as big as very fat hamsters.

“One moonlit night he took his two most trusted crew members, rowed to a tropical island and buried the chest. Then he decided that even his most trusted crew members couldn’t be trusted to keep the secret of where they had hidden it. So he shot them both. It is said that they died with a terrible curse on their lips – a curse on Grungeybeard and his riches.

“And then – nobody knows. There’s some do say he decided that he couldn’t even trust himself not to give away the secret by talking in his sleep, so he shot himself, too. There’s some do say he went stark mad and had a great ship built out of solid gold that slipped straight off the launching ramp and down to the bottom of the sea – taking him and all his crew with it. And there’s some do say he changed his name to Nigel, opened a small tea shop, and spent the rest of his days baking scones.

“And from that day to this, no one ever knew where his treasure lay hidden. Until this map gave up his secret. We’re going to be rich, Eddy my lad. We sail with the tide!”

“Brilliant!” shouted Eddy. “I mean, aye aye Captain! Where do we meet the rest of your crew?”

“Stinky fish!” shouted the Captain. “I knew I’d forgotten something. We needs a crew.”

The shop owner coughed quietly.

“Ahem! I’d love to sail with you.”

“You?” said the Captain, looking her up and down. The shop owner blinked up at him through her spectacles. “Have you ever been to sea?”

“I took the ferry to France once.”

“Can you handle a cutlass in the heat of battle?”

“I’m sure I’d pick it up. I’m a dab hand with a potato peeler.”

“This is a voyage of peril and endeavour. I’d have to be desperate to sail with you on board.”

“Oh,” said the shop owner, trying very hard not to sound disappointed.

“What I needs,” said the Captain, “is a gang of salt-seasoned old sea-dogs, with sailing in their sinews and spirit in their stomachs. Now where in all the wide blue yonder am I going to find them?”