Plot Summary:Sister Marie -Thérèse tries to save the prostitutes doomed to a sad fate ;two of them ,Marcelle and Maria ,are in love with two honest men ,a painter and his best friend .But the girls pretend that they work by night in a post office .An old hooker is killed by a pimp ,and Marcelle is a suspect .The painter could provide her with an alibi,but she does not want him to testify in her favor,for he would know who she really is.