On instructions of the French company Pathé Frères, Alfred Machin develops a film industry in the Netherlands and Belgium from 1912 to the advent of World War One. He directs several quality films including La Fille de Delft, Maudite soit la Guerre and this wonderful gem Le Diamant Noir. A man is accused of theft and decides to quit the country. Machin's favourite pet, the panther Mimir shares the lead roll in this film with a magpie.

Kaatje, the daughter of the miller Schoonejans, and Jef, a little shepherd, who live near Delft, are happy together. In a floral parade, the carriage the two children have decorated with tulips wins the first prize. The next day, during a thunderstorm, lightning destroys the mill and kills Schoonejans. A life of misery starts for his widow and daughter. Remembering how the theatre manager Boolmans had applauded the dancing of Kaatje and Jef at the floral parade, the widow takes her daughter to Amsterdam, where Boolmans engages Kaatje. The years pass, and Kate has become a famous dancer.