In a desperate need of money, The Menaces try all they can to cause crime within Gothius City. However, it's near impossible to do so now that Bathog and the police have learned most of their tricks, making them able to catch the group much more easily. As the group tries thinking of what to do, Argit offers to give up his valuable treasures and exchange it for what it's worth in cash. They agree and Argit makes his way to his ship, with Wild, so he can make the journey to his stored away treasure.
As luck would have it, his brother Bandit shows up at the base and asks where he is. Split explains that Argit needs to retrieve his treasure for them then he suggests Bandit go with him since he is a great treasure hunter too. Bandit agree and ends up meeting Argit which of course isn't happy to see him. As they bicker, however, they soon realize they are heading out to sea as Wild carries out his usual tasks of raising the anchor. Having no choice but to bring Bandit along, the guys journey through the open sea until they reach the portal which takes them to the hidden, legendary land called Everfree Island.
Before Argit rounds up his pirate crew from the island, the islands hero Darren Drew shows up to see if the captain is up to no good. After hearing that Argit is in search for his treasure, Darren reveals the truth about him and the islands inhabitants hiding his treasure on him for fun. Enraged, Argit, Wild, Bandit, and his crew must go in search of the valuables so they search the island, facing many obstacles and unfortunate encounters. Once the treasure is found however, they return to their dimension.
Their misfortune doubles when Argit's greatest rival of the sea, Captain Blackheart, appears. Argit's ship is struck as it often happens when he encounters Blackheart. Now that the treasure is gone once more and with them stranded, the boys must find a way back home before facing more of the dangers of the sea yet to come their way.