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...

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...

Peter Gruber, a young tenor from Vienna, gives piano lessons to Daisy, the daughter of a dentist. They fall in love and when Gruber has to perform in...

Several generations of Mullers go to war with each other over their family business, the main branch of which is about to go belly-up.

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...

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,...