In Murder Most Foul, Miss Marple is present in court as a member of the jury when Leonard Vole is accused of murdering a wealthy widow. While all the other jurors are ready to convict Vole, Miss Marple has her doubts about his guilt. After Vole is found guilty and sentenced to death, Miss Marple becomes even more determined to prove his innocence and clear his name.
As she begins her investigation, Miss Marple uncovers a web of lies and deceit that seems to implicate everyone involved in the case. She discovers that the victim's maid, who was in the house at the time of the murder, had a motive for killing her employer. She also learns that the victim's estranged husband, who was out of the country at the time of the murder, had the opportunity to arrange the crime and frame Vole for it.
As Miss Marple delves deeper into the case, she finds that every suspect has a plausible motive for the murder, and it becomes increasingly difficult to identify the real killer. Eventually, she pieces together all the clues and presents her findings to the police, who are able to apprehend the murderer and exonerate Vole.
Throughout the movie, Margaret Rutherford's portrayal of Miss Marple is both endearing and hilarious, as she uses her unconventional methods of investigation to get to the bottom of the case. Murder Most Foul is a delightful whodunit that will keep you guessing until the very end.