For the Novák and Bartáček families, money is king, and they'll do just about anything to get it. While René Novák pitches his parents a lucrative scheme to swindle as many people with the last name Novák in the country as possible, the Bartáček clan decides to pretend to be much poorer than they really are in order to siphon some dollars from an American relative. And it doesn't take long before these separate scams start to intertwine.

A car deliberately runs down a young man on a road by a small border town. The locals recognize the dead man as one of the students who were there on volunteer work some time before. The police detectives, Major Kalas (Rudolf Hrusínský) and Lieutenant Varga (Radoslav Brzobohatý) can then get on the trail of the people with whom the victim was involved, especially at the photographic studio headed by Bohuslav Pacer (Bohus Záhorský).

To the intolerant and bloody-minded Prague actor Bergner (Milos Kopecký) is the lead in Moliere's Misanthrope which he is studying now as tailor-made. On top of that he is malicious and he advises to the new actress Helenka (Dagmar Havlová) in such a way that she upsets the theatre director. If Bergner accuses somebody of a mischief and he is wrong, he never apologizes. When he almost crashes an older elegant lady by his car on the zebra crossing, instead of an apology he calls her an old ballet dancer... But in Brno's TV he takes part in a discussion on manners and he gives himself as an example of good manners and grace. In the train he meets a magic old man (Ladislav Pesek) who warns him and admonishes him to change his behavior. After he arrives to Prague the old man's threat comes true.

In the forest near the village of Drahovice, a nurse from the local health center is found murdered. Three months ago, another young woman died nearby and a sexual motive was proved in the case of her murder. In the case of the nurse, the motives are not so clear. Two criminologists from Prague - Major Kalas (Rudolf Hrusínský) and Lieutenant Varga (Radoslav Brzobohatý) - patiently collect all available leads and question the villagers.

On the Trail of Blood is a crime movie set in Central Europe. It follows the investigation of a serial child killer and the multiple suspects involved. The plot also includes themes of loss, unhappy marriage, and hidden secrets. The movie delves into the dark underbelly of society and explores the complex relationships between the characters.