Raging Archipelago

Raging Archipelago (per title card) is listed as The Raging Archipelago in TV guides.

Summary
The pirates of Puerto Angel rescue a mysterious stranger named Sansken who is looking to contact the pirates with important information about Kharzem Prison (where Mahad and Lena's mother Mila is being held). The kids follow him to the Raging Archipelago - formerly the city of Paris, hidden in a large atmospheric storm.

It is there that they find themselves in a double-cross when it is revealed that Sansken lured them there to hand them over to the Sphere. After a huge battle with Diwan and Oslo, the children are rescued by Sansken who explains that he was blackmailed by the Sphere in order to save his own two children: his son Cedric and daughter Natalie.