Mount Vesuvius is on the verge of eruption – just when the Djinn twins John and Philippa are on vacation in Naples with their uncle Nimrod. And that's not all: volcanoes around the world are showing threatening activity. With the help of an Icelandic professor, the three Djinn discover that the so-called Hotaniya crystals are the cause of the impending environmental disaster. They are said to be located in the tomb of the famous Mongol ruler Genghis Khan. However, the location of the tomb is unknown. A dangerous journey around the world begins. More than once, John, Philippa, and their helpers find themselves in life-threatening situations. And then they learn that according to an ancient prophecy, the world can only be saved if a pair of Djinn twins sacrifices themselves voluntarily! The seventh and final adventure of the "Children of the Djinn" – as thrilling as none other!.