A fun treasure hunt reveals an unexpected prize. As well as a chest full of chocolate doubloons the ‘goodest goodies’ discover a large egg inside the treasure chest. And it’s not chocolate. In fact, it hatches into a baby pirate dinosaur! When Flinn is smitten and adopts the baby, it soon becomes a monstrous toddler and causes such havoc on board the Acorn they end up returning it to its mother... a ferocious Monster-osaurus who almost eats them all!