The police find nothing to support her story, so she conducts her own investigation, and with the aid of her close friend Jim Stringer, comes to the conclusion that the body must have been thrown off the train near the grounds of Ackenthorpe Hall.

Stringer uncovers the details of Ackenthorpe's will: the family fortune is to go to his long-suffering, attentive daughter Emma; his sons Cedric, Harold and Albert; and Alexander, his intelligent and insightful grandson (A fourth son, Edmund, was killed in the war and a second daughter, Edith, Alexander's mother, died of illness).

In addition, Agatha Christie's suspense and underlying darkness are largely replaced by light, even whimsical touches typical of a comedy of manners.

In the novel, an elderly woman named Elspeth McGillicuddy witnesses the murder, not her friend, Miss Marple, who is introduced later.

[1] Almar Halfidason, a critic for the BBC film website, awarded the picture four stars out of a possible five, calling it "delightfully dotty" and "fun".

[4] MGM's head of British production, Lawrence Bachmann said it was an "exceptionally satisfactory money spinner" and commissioned sequels.