The Mystery of the Old Garden(1984)

A group of teenagers dream of adventures and experiencing something unusual, mysterious and romantic. The boys play treasure hunters and detectives in an old park adjacent to a modern housing estate. By accident, the heroes find the trail of a youth gang that stole the documentation of a sensational preparation that can be used in the preparation of animal feed. The gang members manage to suspect the inventor of the preparation, the engineer Tyc. His son, Andrzej, and his friends decide to expose the real criminals and find maps that are to indicate the place of the hidden treasure.