It is 1955 and the government in Czechoslovakia has declared an amnesty for post-war emigrants. Many of them returned to their families, only young Pavel Kocián's single mother waits in vain for him. Despite her protests, Tomáš Stach, an assembler, is accommodated in her flat as a lodger. Until recently, his fiancée Jana was also waiting for Pavel's return, but she has given up hope and visits Mrs Kocián only out of pity. One evening, an unknown man who introduces himself as Jonáš and claims to know Pavel visits her.

A comedy about exchange of 12 apartments , which, its organizer, lawyer Radosta, rightly called Action Ball Lightning. To prepare, organize and execute the exchange of twelve apartments is a work worthy champions. Radosta, who was excellently played by Rudolf Hrušínský, solved all sudden difficulties and complications on the fly and with grace. To be sure that the on the D-day everything goes well he prepares a little rehearsal, which reveals many minor issues caused for example by wedding ordered to inappropriate term or hesitation of some participants. Last but not least a night exercise announced by drunk psychologist Knotků, creates a lot of confusion that nearly sabotaged the whole operation.

Placek (Josef Kemr), the head of research in a chemical plant, appreciates the help of his younger colleague Bernát (Alois Svehlík) in the creation of a new synthetic material.

The growing conflict between the unruly owner of the villa and his lodger ends up in court. The cohabitation ends in bodily harm - and the film actually translates two versions of the same events, as seen by each of the parties involved. However, the attempt at morality, which proclaimed the necessity of removing the old survivals in people's thinking, did not quite work, and the testimony presented is at times a bit stiff.

In this zany Czechoslovakian comedy, a scientist invents a machine that projects a sleeping person's dream on a screen; disaster soon follows when the machine malfunctions and the cartoon-like dream characters become very real!