Étienne, a very sensitive being, watches helplessly as his mother suffers from his father's infidelities. He tries to seduce his father's next conquest without his knowledge.

1895. Discovery of X-rays. Researchers and scholars are true martyrs, because they do not know how to protect themselves against radiation dermatitis. Professor Belcour has to have one hand amputated, his assistant Henri Vermont, aware of the danger, has the courage to break up with his fiancée. Withdrawn to the countryside, they eventually recover.

Rudolf, the only heir to Emperor Franz Josef of Austria-Hungary, is trapped in a loveless marriage to a Belgian princess. As he seeks to flee his stifling environment, he meets the beautiful Maria, and the two enter into a scandalous affair. Despite the interference of the Emperor, the couple refuse to give each other up.

Jean Larivière receives an impromptu visit from his future father-in-law while Lina, his mistress, learning of his marriage, has come to make a scene. The baron is seduced by Lina, and Jean, noticing that Angélique, his fiancée, is not so bad after all, is very happy to marry her.