In my opinion, to create interest in the film, you need to partially play a spoiler. Especially since the essence is revealed almost at the beginning of the film.
And the essence of the tragedy is that a woman at 16 gave birth to a boy (Mark), and her parents arranged for the adoption of this child by complete strangers. Fate made fun of him. When the boy grew up, he decided to find his biological mother and punish her for betrayal.
About how it was organized, the film tells. He doesn't exonerate Mark's mother, nor does he condemn his son's actions. He simply tells, in the spirit of Agatha Christie’s detectives (but in modern coloring), how thoughtful and masterfully executed everything was.
Although the beginning is somewhat tedious, subsequent events justify this slowness.
The film very professionally reveals the birth of a psychopath in a deprived parental love child. Look at that. This is a great work of Danish filmmakers.