In the organizer's words:

The summer vacation has begun and The Three?? want to go on a road trip. But just as Justus Jonas (JULIUS WECKAUF), Peter Shaw (NEVIO WENDT) and Bob Andrews (LEVI BRANDL) are about to set off, the phone rings at headquarters and an unknown caller hands the trio of detectives their latest case. Needless to say, their vacation plans are quickly forgotten. The three boys follow the clues and come across the secret society Sphinx around the mysterious archaeology professor Phoenix (ANDREAS PIETSCHMANN) and his assistant Olin (JANNIK SCHÜMANN). Sphinx carries out illegal excavations and sells the stolen art treasures. They soon set off on an expedition to the active volcanic island of Makatao, also known as the Isle of the Dead. This is because the resting place of an ancient people is said to be cursed: No one who enters Makatao comes back alive. Why does Sphinx embark on such a daring journey? And what does the successful entrepreneur Joseph Saito Hadden (SIMON KLUTH) have to do with the expedition?