Curious Tobi receives a mysterious, locked treasure chest. Only one person has the key: Marina - Tobi's best friend from childhood. But where is she?

The search for her kickstarts a great adventure that takes Tobi all around the world to the most stunning places. Out of the blue, Tobi receives a mysterious treasure chest. But the chest is locked and only one person has the key: Marina – a circumnavigator and Tobi's best friend from childhood. But where is she? Tobi's search for Marina kickstarts his greatest adventure yet.

The journey takes him to Vietnam to the largest cave in the world, into the famous Hạ Long Bay with its thousands of limestone islets, across the stormy South China Sea, to nomads in the Mongolian steppes and on to the indigenous peoples of the Amazon rainforest in Brazil. Always with one goal in mind: solving the riddle of the treasure chest and finding the mysterious flying rivers.