In this essay the composer talks about why he and librettist Nicholas Wright worked from Winston Graham’s novel rather than the Hitchcock film, how he set a psychiatrist’s session and a fox hunt for the stage, and how to deploy English National Opera’s chorus. (Favorite line, about “the Marnettes”: “The effect should be as if her inner monologue is actually a warped recording of the Tallis Scholars singing a single chord from an obscure Tudor motet.”)