Jean Fleury, a young engineer who has designed a revolutionary engine for the Revoil motor company, is engaged to Aimée Valois, a seamstress, his neighbor across the hall. But the charming young lady is hired one day by a nightclub and lets herself be lured by the easy life in Paris. So much so that, to Jean's great distress, she breaks up with him. But, along with time, Aimée gets tired of her vain and frivolous lifestyle and comes back to Jean..