A house in Paris happens to have two families living there with the same last name. In one apartment lives opera singer Gambetta Duval with his two daughters, Jeanne and Nita. In the second apartment lives old lady Duval with her grandchild Philippa and an her lodger, the physician Leon Monnier. Jeanne is secretly in love with Dr. Monnier who is secretly in love with Nita, who is secretly having an affair with the great playwright Armand de Marny.

The son of a Countess runs away to join the circus and becomes a great trapeze artist. He returns years later and falls in love with a young woman.

It can hardly be said that things are peaceful in the Berlin apartment building where the film's story takes place. There are constant clashes between the residents – and sometimes that's quite literal: for example, when the widow Bock hid some explosives among the bricks, which detonated when the building's thieving doorman lit them in his stove.