When famous detective Nick Carter visits Prague, he becomes involved in strange case of a missing dog and even stranger carnivorous plant. He becomes convinced that he is standing against his greatest enemy, the Gardener, who supposedly died years ago in a swamp...

A trespassing gang of boys encounter a ghost in the ruins of a castle. When they rescue the ghost who is caught in a trapset, they become allies in a fight to prevent ruins from being turned into mushroom farm by the city authorities.