Question: Paul Dehn was the screenwriter for which 1974 British mystery?

Context paragraphs:
Paul Dehn: Paul Dehn (5 November 1912 – 30 September 1976) was a British screenwriter, best known for "Goldfinger", "The Spy Who Came in from the Cold", "Planet of the Apes" sequels and "Murder on the Orient Express".  Dehn and his partner, James Bernard, won the Academy Award for best Motion Picture story for "Seven Days to Noon".

Seven Days to Noon: Seven Days to Noon is a 1950 British drama / thriller film directed by John and Roy Boulting.  Based on the book, "Un Nazi en Manhattan", written by Fernando Josseau, Paul Dehn and James Bernard won the Academy Award for Best Story for this film.

The Deadly Affair: The Deadly Affair is a 1966 British espionage–thriller film, based on John le Carré's first novel "Call for the Dead".  The film stars James Mason, Harry Andrews, Simone Signoret and Maximilian Schell and was directed by Sidney Lumet from a script by Paul Dehn.  In it George Smiley, the central character of the novel and many other le Carré books, is renamed Charles Dobbs as Paramount, which owned the film rights of their recently filmed "The Spy Who Came in from the Cold", had the rights to the Smiley character.  The soundtrack was composed by Quincy Jones, and the bossa nova theme song, "Who Needs Forever", is performed by Astrud Gilberto.

Conquest of the Planet of the Apes: Conquest of the Planet of the Apes is a 1972 science fiction film directed by J. Lee Thompson and written by Paul Dehn.  It is the fourth of five films in the original "Planet of the Apes" series produced by Arthur P. Jacobs.  The film stars Roddy McDowall, Don Murray and Ricardo Montalbán.  It explores how the apes rebelled from humanity's ill treatment following "Escape from the Planet of the Apes" (1971).  It was followed by "Battle for the Planet of the Apes" (1973).

Ghost Story (1974 film): Ghost Story is a 1974 British mystery film directed by Stephen Weeks and starring Marianne Faithfull, Leigh Lawson, Larry Dann and Anthony Bate.  Although set in England, the film was almost entirely shot on location in India, much of it at Bangalore Palace, owned by the Maharajah of Mysore.  The film features a rare performance from actor Vivian MacKerrell, who was later the inspiration for Withnail in Bruce Robinson's "Withnail and I".  The story and screenplay are by Philip Norman, Rosemary Sutcliff and Stephen Weeks and music is composed

The Bear (opera): The Bear is the second of the two operas by William Walton, described in publication as an "Extravaganza in One Act".  The libretto was written by Paul Dehn and Walton, based on the play of the same title by Anton Chekhov (which is also sometimes translated into English as "The Boor").

Beneath the Planet of the Apes: Beneath the Planet of the Apes is a 1970 American science fiction film directed by Ted Post and written by Paul Dehn.  It is the second of five films in the original "Planet of the Apes" series produced by Arthur P. Jacobs.  The film stars James Franciscus, Kim Hunter, Maurice Evans, and Linda Harrison, and features Charlton Heston in a supporting role.

Murder on the Orient Express (1974 film): Murder on the Orient Express is a 1974 British mystery film directed by Sidney Lumet, produced by John Brabourne and Richard B. Goodwin, and based on the 1934 novel of the same name by Agatha Christie.

Escape from the Planet of the Apes: Escape from the Planet of the Apes is a 1971 science fiction film directed by Don Taylor and written by Paul Dehn.  It stars Roddy McDowall, Kim Hunter, Bradford Dillman and Ricardo Montalbán.  It is the third of five films in the original "Planet of the Apes" series produced by Arthur P. Jacobs, the second being "Beneath the Planet of the Apes" (1970).  Its plot centers on many social issues of the day including scientific experimentation on animals, nuclear war and government intrusion.  The film was well received by critics, getting the best reviews of the four "Planet of the Apes" sequels.  It was followed by "Conquest of the Planet of the Apes".

The Night of the Generals: The Night of the Generals is a 1967 Franco-British-American Second World War crime mystery film directed by Anatole Litvak and produced by Sam Spiegel.  It stars Peter O'Toole, Omar Sharif, Tom Courtenay, Donald Pleasence, Joanna Pettet and Philippe Noiret.  The screenplay by Joseph Kessel and Paul Dehn was loosely based on the beginning of the novel of the same name by German author Hans Hellmut Kirst.  The writing credits also include the line "based on an incident written by James Hadley Chase".  Gore Vidal is said to have contributed to the screenplay, but was not credited.

Supporting paragraphs: Paul Dehn Murder on the Orient Express (1974 film)
Answer: Murder on the Orient Express