Little Scallop should be happy. She's a princess of the Mollusk tribe, rulers of beautiful Mollusk Island. And she has two fun friends - Aqua and Surf - who just happen to be mermaids. But Little Scallop is bored. Her warrior brothers are allowed to do exciting things, like spying on the pirates who live on the other side of the island. Little Scallop longs to have a real adventure. When Aqua and Surf invite her to go pearl-diving - even though she knows she shouldn't - she can't resist. So late one night, she sneaks off into forbidden waters with Aqua and Surf. That's when the trouble starts - they run into a fierce storm and a strange ship sailed by men who would love to capture a mermaid. Soon, Little Scallop is caught up in the adventure she always wanted. The question is: can she and her friends get out of it?

While Peter is away from the island, James and the other Lost Boys discover a mysterious cave. Shining Pearl and her sister, Little Scallop, warn the boys that the cave is a dangerous place, inhabited by a creature known as the Goat Taker - a beast so scary that even the Mollusk tribe fears it. But the boys can't resist trying to discover the cave's secrets. When the first of those secrets turns out to be a tantalizing hint of a famous haunted treasure, Captain Hook and his band of cutthroat pirates quickly join the hunt. Before long, the children are fleeing for their lives in a dark and deadly underground labyrinth...and their only hope of escape is to solve the mystery of the Cave of the Dark Wind.

When an earthquake strikes Never Land Island, things begin to go terribly wrong. A mysterious barrel washes ashore and falls into the hands of Captain Hook, who hatches an evil plan. The once-peaceful mermaids, who have always been friends to the natives, have turned violent. When the mermaids injure some members of the Mollusk tribe, the warriors have no choice but to fight back. Meanwhile, the boys and Shining Pearl and Little Scallop set off on a secret mission to try to make peace with the mermaids. Instead, they’re captured, and while in captivity they discover the cause of the problem—Blood Tide is poisoning the lagoon and will eventually kill the mermaids. With time running out, the children must figure out a way to save the mermaids and to stop Captain Hook, whose plan threatens to destroy the Mollusk village and change life on Never Land Island forever.