The Mirror Crack'd (1980)

In 1953, the small English village of St. Mary Mead, home to Miss Jane Marple (Dame Angela Lansbury), is delighted when a big American movie company arrives to make a movie telling of the relationship between Jane Grey and Elizabeth I, starring famous actresses Marina Rudd (Dame Elizabeth Taylor) and Lola Brewster (Kim Novak). Marina arrives with her husband Jason (Rock Hudson), and when she discovers that Lola is will be in the movie with her, she hits the roof, as Lola and Marina loathe each other on sight. Marina has been getting death threats, and at a party at the manor house, Heather Babcock (Maureen Bennett), after boring Marina with a long story, drinks a cocktail made for Marina, and dies from poisoning. Everybody believes that Marina is the target, but the Police Officer investigating the case, Chief Inspector Dermot Craddock (Edward Fox) isn't sure, so he asks Miss Jane Marple, his aunt, to investigate.