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.
A captain saves a kidnapped magnate from a nursing home run by foreign agents.
After the death of their father, a travelling showman, Iris Belmore and her little brother Billy are engaged to play in a circus owned by George Munro. Jim, a young man their father had adopted, comes home after he has been at the sea, where he has saved the lives of Lady Rosemount and her son during a shipwreck. Jim, a sharpshooter, also joins Munro’s circus and shows Iris and Billy much kindness. Iris and Jim do a sharpshooting act together. Munro’s jealousy is aroused when he sees that their friendship is growing into love. In revenge he tampers with Jim’s revolver, with the result that an accident happens in the ring and Iris is slightly wounded. Jim gives Munro a severe thrashing and leaves the circus, taking Iris and Billy with him, in search of other employment. While tramping the country, they meet Lady Rosemount and her husband. Sir Henry, hearing their story and wishing to show his gratitude, buys Munro’s circus and makes Jim the manager, on condition that he marries Iris. ×
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.
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.
Young poacher Hendrik van Norden has seriously wounded a game-keeper, who has not recognized him. There was, however, one witness: captain Van Oort, but he promises to keep silent. Five years later Hendrik has become a lighthouse-keeper and is courting Annie. Van Oort is also trying to win Annie's affections, and in his jealousy he decides to remind Hendrik of what he knows about his past...