Cardinal Richelieu gives the order that the twin brother of France's King Louis XIV should be removed from the court and taken to the country. There he is educated, without knowledge of his true ancestry, and kept as a prisoner.

A millionaire daughter is to be married to a man unknown to her. To get to know him, she slips into men's clothes, sticks on a mustache and is hired as a chauffeur.

Richard de la Croix's brother, Andreas, has been driven insane by a notorious vamp and socialite named Sappho. A friend takes Richard to the Odeon to meet her, but when Sappho actually meets him, he is unaware that she is the woman who drove Andreas to be institutionalised. Sappho genuinely falls in love with Richard, and decides to leave her vampy ways and her older lover behind her so that she can have him.

Weltbrand is the first part of the two-part silent movie Christian Wahnschaffe.

Conrad Veidt plays a famous musician who is blackmailed for being gay. Eventually he stands trial and is convicted. At the end the film pleads for the abolition of §175 (the paragraph which punishes homosexuality).