Soupçons(1956)

"Poisoner" - After her fiancé is arrested Claire finds herself alone and forced to find work. She is hired by a country squire, Etienne de Montenoy, as the tutor of his goddaughter. It does not take long before Montenoy falls for her but a little longer before the young woman, reluctant at first, understands Etienne loves her truly and then requites his love. Etienne lives so happily with her that he decides to make her his heir. Shortly after, he is murdered by poison...