After WWII, Berlin lies in ruins. For Gustav, Willi and their friends the rubble provides an adventurous, dangerous playground. Especially for Gustav, it helps pass the time, as he longs for his father's return from a POW camp. One day a stranger arrives, looking helpless and hopeless.
A German expedition is in the African jungles on an unidentified misson. During this mission one of the German explorers, Thoren, is attacked and captured by the local natives called the Botos.
Strange things happen in a revue theatre. The dancer Maria seems to be hunted by an invisible admirer. When the body of a probable FBI agent is found in a trunk the police asks FBI man Joe Como for help. Como gets interested in the revue theatre and an ominous transport firm soon. When he is receiving mysterious threatening letters he is sure that Dr. Mabuse has risen again. But what is going on at "Enterprise X" so that both the goverment and the mad genius in crime are interested in it?
