Join Basjan, Matilda and the Van der Branders as they sail the seven seas (and the coast of Grootgaapbaai) in search of adventure and pirate loot. Every full moon, a mysterious ship is seen off the coast of Grootgaapbaai. Then, the day after, gold and jewellery are missing from the homes, shops and museums of the town. Matilda needs the Seerowers' help to investigate. Can Matilda and Basjan retrieve the stolen booty from the mysterious ship before the moon fades? Or will they end up stuck on board with ghostly pirates until the next full moon?