The Draughtsman's Contract (1982)

R. Neville, a brash young draftsman, is hired to make a dozen landscape illustrations at the estate of Mr Herbert and his wife Virginia. Aside from monetary compensation, the arrangement includes a sexual liaison offered to Neville by Virginia while her estranged husband is away. But when the murdered body of Mr Herbert is discovered at the estate, mysterious clues found in Neville's drawings point to the identity of the killer.