After receiving his degree from Cambridge, Shaffer and his twin brother Peter co-authored two novels under the pseudonym Peter Anthony before each carved out a niche on stage and in films. His first play, "The Savage Parade" was produced in 1963. Shaffer segued to features with "Mr. Forbush and the Penguins/Cry of the Penguins" (1971), a drama about a young biologist in the Antarctic. In addition to "Sleuth," about a mystery writer leading his wife's lover into a diabolical trap, other Shaffer screenplays include Alfred Hitchcock's "Frenzy" (1972), about an innocent man suspected of being a serial killer, the eerie thriller "The Wicker Man" (1973) and three adaptation of Agatha Christie mysteries, "Death on the Nile" (1978), "Evil Under the Sun" (1982) and "Appointment with Death" (1988), all starring Peter Ustinov as Belgian detective Hercule Poirot. In 1993, Shaffer co-wrote the story adaptation for "Sommersby," based on the French "Le Retourne de Martin Guerre," about a man who comes back from war, but is impersonating another man.