Dr. Robert Hart visits his friend Ursula von Hohenau in Saxony in July 1914. There he hears about the Austrian ultimatum to Serbia. He immediately returns to his home town where, just before mobilisation, he meets the Polish count Bransky and his daughter Jadwiga, the French Vicomte Latour and the Russian counsellor of embassy count Bronislaw Krascinsky. Bronislaw is madly in love with Jadwiga and jealous of Dr. Hart. After the outbreak of the war Dr. Hart works close to the Polish frontlines. Bronislaw leads the Russian troops in this area. When Bronislaw is wounded during a battle with the Germans Dr. Hart finds him and takes care of his wounds.

Gwynplaine, son of Lord Clancharlie, has a permanent smile carved on his face by the King, in revenge for Gwynplaine's father's treachery. Gwynplaine is adopted by a travelling showman and becomes a popular idol. He falls in love with the blind Dea. The king dies, and his evil jester tries to destroy or corrupt Gwynplaine.