When his granddaughter is born, debt-ridden Colonel von Zwenken misses out on Aunt Roselaar's allowance of 20,000 guilders. Anxious to keep the money, his son-in-law telegraphs the aunt that a son was born, Frans, and the girl is brought up as a boy. Based on the novel by Anna L.G. Bosboom-Toussaint.

When his colleague presents him with (forged) evidence of his wife Sylvette's unfaithfulness, factory owner Jean Sourdier kills him in a fit of rage. After fifteen years in prison he is determined to take revenge on his wife by killing Ninette, a daughter from her second marriage.

This government commissioned film -- made on the occasion of the forty year anniversary of queen Wilhelmina's reign -- chronicles the lives of two Dutch families from 1898 to 1938 against the backdrop of the social and political events of the times. It shows the emergence of trade unions, the troubled years of the First World War, the development of aviation and Schiphol airport, the Dutch East Indies and the lives of the Dutch royal family.

Still coming to terms with the death of her mother, Willy Verhulst loses her father as well -- just as she is about to sit her final exams. She manages to pass, and as she is trying to find a job she remembers a young man she met in the hospital. The boy, Herder, works for a radio station and gives her a job as a secretary.

Judy Aalders grows up in an orphanage. Albert Woudenberg happens to be present when Judy confronts the trustees of the orphanage and is expelled. He decides to send her to university and Judy, who has only ever seen his shadowy long legs, refers to him as 'Daddy-Long-Legs' from that day. Not knowing he is in fact her benefactor, Judy's relationship with Albert gradually turns into love.

In Pygmalion, a professor named Henry Higgins takes on a bet to transform a Cockney flower girl, Eliza Doolittle, into a refined lady by teaching her proper English and manners. As Eliza undergoes a remarkable makeover, she and Higgins develop a complex relationship filled with misunderstandings and humorous situations.

Mobilization on the brink of the Second World War divides a husband and wife. When lawyer Frans van Loon is called up to join the mine clearance service he doesn't want to worry his wife and keeps it from her. His secretiveness leads her to believe he doesn't love her anymore. She subsequently falls for the charms of an actor. When Frans finds out, a violent quarrel ensues.

The secret from the title is the lost recipe for shiny Delft pottery, that Jan Vogel is desperately trying to rediscover. For his attempts he needs platinum, but the funds run out because the factory owner Van Haaften has lost his money in stock-speculations. Luckily for Jan, he finds a farewell letter in the park, including a large sum of money. Meanwhile, the owner's son Leo confesses his love for Jan's daughter Annie, but Van Haaften forbids their marriage.

In the prologue, a boat with some shipwrecked persons is drifting at sea. Among them is Baron van Waldheim, who, before he dies of exhaustion, entrusts his little son Alfred to the care of his butler Hendrik. The evil Jan van Oort persuades Hendrik to give him the Baron's papers. When they put the boy ashore, he wounds himself on a nail (leaving a scar that will later prove his identity). For years Van Oort manages to pass himself off as Baron van Waldheim; he is married and has a daughter and a son. One day Hendrik turns up demanding a job as butler, swearing that otherwise he will betray Van Oort's secret. Meanwhile, Alfred - now an adult known as Ulbo Garvema - has become a teacher. Unaware of who Van Oort really is, he accepts the position of tutor to Van Oort's children. He falls in love with the daughter, but Van Oort refuses to give his consent to their marriage. Ulbo and the girl elope.

The devil has arrived in Amsterdam, hell-bent on bombarding a poor girl, a wealthy banker and a young painter with great misfortune. This film is presumed lost.