The young crusader Joseph Kraft took possession of a book by one of Pythagoras' students, which described how to make an instrument to control humanity - the flute of omnipotence. Joseph devoted his whole life to creating a flute, but did not dare to use it, realizing how dangerous the invention was. The famous rat catcher of Hamelin, into whose hands the instrument fell, also realized that the magic flute leading him along would not return him his lost happiness... An insurance company employee, Bertha, was involved in the investigation of the theft of a huge diamond brought to an international exhibition. But she couldn’t even imagine that this case would help her get closer to solving the mystery of the Hamelin rat catcher and find the current owner of the powerful flute.