Life smiles at Dr. Raymond Marty: he works as a researcher with professor Monbel, a man he deeply admires. On a personal level things are fine as well since he is about to marry Germaine, the prof's daughter. But life turns sour the day Madame Reinher, a dangerous vamp, sets her sights on the young man. And as Raymond refuses her obstinately, the embittered siren decides to compromise him in the presence of his future father in law. She unfortunately pulls it off, which causes Montel to break the engagement. Broken-hearted, Raymond nonetheless resists the renewed assaults of the devilish countess. But things, good or bad, must come to an end and one day the tide turns: Lili, Madame Reinher's little girl happens to fall seriously ill and her life is saved only thanks to the joint efforts of Martyl and Monbel, who have been sent for. Thankful to the two men, the countess eventually brings herself to confess the nasty trick she played on Raymond.