4.50 from Paddington is a detective fiction novel by Agatha Christie, first published in November 1957 in the United Kingdom by Collins Crime Club. This work was published in the United States at the same time as What Mrs. McGillicuddy Saw!, by Dodd, Mead. The novel was published in serial form before the book was released in each nation, and under different titles. The US edition retailed at $2.95.

Miss Jane Marple is a fictional character in Agatha Christie's crime novels and short stories. Miss Marple lives in the village of St. Mary Mead and acts as an amateur consulting detective. Often characterized as an elderly spinster, she is one of Christie's best-known characters and has been portrayed numerous times on screen. Her first appearance was in a short story published in The Royal Magazine in December 1927, "The Tuesday Night Club", which later became the first chapter of The Thirteen Problems (1932). Her first appearance in a full-length novel was in The Murder at the Vicarage in 1930, and her last appearance was in Sleeping Murder in 1976.