Screenwriter Anthony Shaffer had previously penned critically praised adaptations of Sleuth and Frenzy (for Alfred Hitchcock).
I am referring, of course, to the 1973 The Wicker Man directed by Robin Hardy and written by Anthony Shaffer at the absolute peak of his influence - it was three years after Sleuth was staged, and one year after it was filmed in the same year as Shaffer's script for Alfred Hitchcock's Frenzy - and not at all the Neil LaBute/Nicolas Cage thing from 2006 , as has come to be regarded in later years as one of the truly misbegotten projects of the 2000s, and a film that has never been described by anyone as "all-time perfect" in any context at all.
Written by Anthony Shaffer, who also adapted Hitchcocks "Frenzy" and penned both the play "Sleuth" and its later film version, the film masterfully builds a sense of discomfort and dread in the viewer, even though nothing particularly scary happens through the bulk of it.