Four policemen have shot down Albert Thoulouse's daughter by accident but are acquitted of all charges. Such injustice infuriates the unfortunate father, who abruptly turns from Jekyll to Hyde. Without giving them a second chance, Albert executes two of the men and swears that he will go to the end of his "mission". But, being reported as suspect N°1, he cannot go back to his home. One night he gets to know Claire, a young movie usherette, who accepts to accommodate and help him...