Three children - Thomas the Fire, Marie the Fearless, Willy the Smart - and their faithful parrot companion Mr. Moody adore the sea and mysteries. They often go out to sea on a real small ship. The life of little pirates is full of exciting adventures: sometimes they came across the "Flying Dutchman", then they ended up on a deserted island, then they returned the world's largest diamond to its owner, then they hunted down the chest of the old pirate Morgan. Many challenges will befall the little adventurers, and in the end they will find out what is more valuable than all the treasures of the world.