Charles Vigne, a wealthy banker, frees Abdul, a good genius imprisoned in a vase. To thank him, Abdul grants his wish: to become a child again, while retaining the experience he has acquired. But the "disappearance" of the banker panics the financial markets and has disastrous consequences for the bank. Eventually, Charles Vigne will ask Abdul to give him back his real age.

The professional and sentimental misadventures of Maurice, a young engineer who works unsuccessfully on the development of a new model of airplane.

Marie, a young bourgeois and Jean, a cargo sailor have an affair, she becomes pregnant but he has to go back to the sea. Marie leaves for Paris where she meets Pierre and marries him. War breaks out, Jean and Pierre will befriend each other on the front.

The children born from a first marriage of a widower and a widower who have remarried do not get along. Frequent quarrels break out in the household which finally finds calm thanks to the presence of a new little girl.