Spending a holiday on a boat and with their grandparents could mean only one thing to the children: it was going to be fun. But they could never have dreamt they would discover pirates and the enchanted world of mermaids. Jack and Abbie's adventures in the dinghy lead them to meet Captain Pearly and find out the reason for him hiding in the cave while Lola and Bella encounter Lisel, the mermaid who takes them on an enchanted ride to meet her mermaid friends and their pets. Captain Pearly takes Jack and Abbie to meet his shipmates and they show them their 'treasures of the sea' in a most amusing way. When Lola and Bella show Jack and Abbie their gifts from the mermaid, they know the pirate is telling the truth.