They're Playing with Fire (1984) on Netflix

During the opening sequences, a college student is seduced by his college professor. After that, it is disclosed that her husband has concocted a devilish scheme to steal millions from an inheritance fund run by his dotty grandmother and totally nasty mother. However, all of that is cast aside for the goings-on of a masked lunatic who is slaughtering the cast in best Jason style. —John Sacksteder wife leaves husbandkissing a married womansex in beddysfunctional marriageadulterous wife32 morePlot summaryAdd synopsisTaglinesFrom his French maid, he got Private Lessons. Now his English professor is giving him a REAL education.GenresCrimeHorrorThrillerCertificateRParents guide