On the verge of getting married to Marijke, young and insecure detective Jozef is assigned the case of a murdered factory girl. His relationship is threatened when he becomes madly infatuated with Carmen, the alluring prime suspect.

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.

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.

The guests at Count Otto von Trepow's East Prussian estate Gross-Ehrenfeld are Lord and Lady Ruthven, Mr Hendriks with his wife and foster-daughter Mariska, a gypsy they adopted years ago, Kundry, the fiancée of Otto's son Bernhard, and Count Stanislaus Larinski, who claims to be a Polish revolutionary wanted by the Russian government. A boating trip is organized but ends when the motor breaks down. While waiting for it to be repaired, the guests go to an inn run by Andreas and his daughter Käthe. Hendriks goes for a walk, sees the boat come back and that a man with a bent back leaves it. He notices that Kundry is afraid of Bernhard.

The wealthy De Roquevilles, the family of alcoholic veteran Jean Laurent, and that of farmer Godard; all have to deal with the outbreak of the Great War. To complicate things even more, Godard's daughter Anny falls in love with young Mario Laurent, who turns out to have inherited some of his father's vices. First part of Maurits Binger's epic silent trilogy.

Ducrot and Ninette accuse Mario and Anny of owing their wealth to the murderous effects of Mario's bombs. Anny leaves for the front to care for the wounded. Third part of Maurits Binger's epic silent trilogy. Most of the film is considered lost – a single fragment remains.

Anny helps Mario escape from prison after his attempted murder of Gaston de Roqueville, who is now married to Ninette. Banker Sorga, an enemy spy, attempts to steal Mario's latest invention: a powerful explosive that could alter the course of the war. Second part of Maurits Binger's epic trilogy, now considered lost.

Married housewife Alda decides to become a singer under the stage name 'La Renzoni', in a duo-act with her father. All goes well, until her husband mistakes her father for her lover...

Lona, a young woman who has no memories of her past, has been adopted by the rich industrialist Van Haaften. She is loved by Henri van Rhenen, a neighbour whose mother still mourns the loss of her daughter, who disappeared twenty years ago under mysterious circumstances. Lona has another suitor, Frans van Borselen, who hopes to marry her so that he can pay his gambling debts with her foster-father's money. Van Haaften discovers that Frans has been cheating at cards and offers him a revolver so that he can end his life honourably.

The happy life of Sylvia and Pieter is disrupted when Sylvia loses her sight and her sister Lyda falls in love with her husband.

Beppie, Margie and Lola, the three talented daughters of American millionaire James Brown, set course to Amsterdam with their art teacher ms. Polly Dewar. There all three of them fall for the charms of attractive tenor Adelqui, the boyfriend of famous diva Anny.

When Jacques, the ladies' tailor of fashion house "The Four Seasons", wins 100,000 guilders in the lottery, his world is suddenly full of opportunity. Shop owner Madame Georgette, however, tries to trick him into signing a rather unfavourable contract.