Miss Marple: The Moving Finger (1985)

Her old friend Maude Calthrop, wife of the village vicar, summons Miss Marple when several of the local residents receive a poison pen letter. All of the recipients thus far are men and all are accused of some act of moral turpitude. When the local solicitor's wife, Angela Symington, is found dead with a poison pen letter at her side, the coroner rules that she took her own life. Not surprisingly, Jane Marple disagrees and is convinced it was murder. When a second villager is killed, it appears Miss Marple is correct. She also deduces the real purpose of the letters.