A certain "unpleasantness" requires the refined sleuthing of the blue-blood detective Lord Peter Wimsey (Ian Carmichael). Both the wealthy General Fentiman and his older sister Lady Dorland expire on the same day, and the distribution of their legacy amongst the surviving heirs depends on who died first. A cloud of mystery surrounds both deaths, leading Wimsey on a trail littered with greed, jealousy, passion, anguish, betrayal, and a rather bitter truth.