Alfred Boulard, a good-natured electrician, gives his blood to save Mona Thalia, a great theater actress. Mona Thalia survives and Boulard becomes the man of the hour. Grateful to him, Mona helps Alfred to become a singing star. But his fame will be short-lived.

Isidore Lechat is a ruthless self-made man whose money allows him to humiliate the others, particularly a ruined noble: he wants his daughter to marry this marquis's son but the girl is in love with a young scientist.

Professor Louis Delage is a kidney transplant specialist. He is so good in his field that his peers nickname him the "great man". But one day, one of his patients die during surgery and Delage starts doubting. Is he actually such a great man? To fight desperation he decides to take in the deceased child while devoting more time to Florence, his hitherto neglected wife.

In 1914, in the first months of World War I, Louise Jarraud loses her husband, killed on the front. Shortly after, she gives birth to a baby, who soon dies. Devastated by this double misfortune, Louise decides to dedicate her life to caring for the children of others. She becomes a nurse with several employers, giving her affection to little boys or girls. A widower and another man propose to her but she refuses twice determined as she is to live only for the children in her charge.

Friends since infancy, two youngsters struggle as their platonic bond blossoms into romantic love with adolescence.