"The 39 Steps" (1935) is a British thriller film directed by Alfred Hitchcock, loosely based on the adventure novel The Thirty-Nine Steps by John Buchan. The film stars Robert Donat and Madeleine Carroll. Of the four major film versions of the book, this film has been the most acclaimed. In 1999, the film came in fourth in a BFI poll of British films. In 2004, Total Film named it the 21st greatest British movie of all time.

Canadian Richard Hannay (Robert Donat) is watching a demonstration of the superlative powers of recall of "Mr. Memory" (Wylie Watson) (a man with a photographic memory) at a London music hall theatre when shots are fired. In the ensuing panic, he finds himself holding a seemingly-frightened Annabella Smith (Lucie Mannheim), who talks him into taking her back to his apartment. There, she tells him that she is a spy, being chased by assassins, and that she has uncovered a plot to steal vital British military secrets, masterminded by a man with the top joint missing from one of his fingers. She mentions the "39 steps", but does not explain its meaning.