4.50 from Paddington

A friend of Miss Marple's, Mrs. McGillicuddy, is travelling on the 4.50 from Paddington when she sees a man strangling a woman on a neighbouring train. The police turn up nothing and don't believe her but Miss Marple does. She believes the answer to the mystery lies at nearby Rutherford Hall. She enlists the help of her resourceful, energetic niece Lucy Eyelesbarrow, who investigates Rutherford Hall by working there as a housekeeper.