Svante is a young boy who lives with his family in a Stockholm apartment. One day he meets Karlsson, a chubby little man in the prime of his life, who can fly using a propeller on his back and who lives in his little house on the roof.
Samuel Plottner is a stockdealer who only wants to get richer, but suddenly things starts to get complicated: His sons meets their longlost mother which not only is after Samuels money, but also can tell them what happened to them the day they were born. The financial expert Benny Hörnsteen is also after Samuels money, and so is the clown Conny Corny and Lennart K. Brons too. How will this end?
In the small working community, the entry in the local newspaper hits like a bomb. The signature "Leif" claims that the town's large arms company Rotum exports weapons illegally. Gunnar Volt, CEO of Rotum, gets a shock. Imagine that someone has the audacity to say that about the community's pride Rotum - even if it now happens to be true. He immediately gathers the management and everyone agrees: Leif must be found - and stopped. But who is this mysterious Leif?
