Warning: Wikipedia contains spoilers.
In this book Miss Marple investigates the murder of Heather Badcock, after she consumes a poisoned drink apparently meant for actress Marina Gregg.
One movie, The Mirror Crack'd (1980), has been made from this book . It starred Angela Lansbury as Miss Marple, as well as Elizabeth Taylor (Marina Rudd), Geraldine Chaplin (Ella Zielinsky), Rock Hudson (Jason Rudd), Tony Curtis (Marty Fenn), Edward Fox (Inspector Craddock), and Kim Novak (Lola Brewster). A television movie, Mirror Crack'd From Side To Side, was made in 1992, starring Joan Hickson as Miss Marple.
The motive behind the murder is similar to an incident in actress Gene Tierney's life. Tierney had contracted German measles early in her pregnancy, resulting in the birth of a developmentally-impaired daughter. Tierney later discovered that she had probably contracted the disease from a fan who had snuck out of quarantine to meet her.
The book's title comes from the poem The Lady of Shalott by Alfred, Lord Tennyson.