Murder Most Foul (1964)

Margaret McGinty, a barmaid and former actress, is found hanged, and her lodger, Harold Taylor, caught at the scene, seems plainly guilty. Everyone believes it to be an open-and-shut case ... except for Miss Marple. She is the lone holdout in the jury that tries him, leading to a mistrial.

Despite the disapproval of Inspector Craddock (Bud Tingwell), Miss Marple decides to delve into the case. She poses as a gatherer for a church 'jumble sale' to enter and search Mrs. McGinty's home. She finds a newspaper with words cut out and several programs for a murder mystery play, Murder She Said, recently performed in the town. These clues lead her to suspect Mrs. McGinty of blackmailing a member of the repertory company.

She auditions for the repertory theatre players, the Cosgood Players, under their actor/manager Driffold Cosgood (Ron Moody). Cosgood is unimpressed by her acting ability, but as she is willing to work for free and mentions she is independently wealthy, takes her on. Miss Marple knows she is on the right track when actor George Rowton (Maurice Good) is poisoned moments later. She secures accommodation in the boarding house in which the cast are staying to further her investigation and Cosgood leaves a copy of his play Remember September in her bedroom to read. Narrowly avoiding an attempt to silence her (one which claims the life of another actress by mistake), Miss Marple unmasks the killer. Cosgood appeals to her to finance Remember September, but she says "Mr Cosgood, whatever else I am, I am definitely no angel."