Peter Ustinov makes his second appearance as Belgian detective Hercule Poirot in this adaptation of the popular Agatha Christie mystery. When noted stage star Arlena Marshall (Diana Rigg) is found murdered while visiting a posh island resort, Poirot is called upon to find the culprit, but given Marshall's shrewish personality and propensity for making enemies, the question isn't Who wanted to see her dead? but Who didn't? The suspects include Rex Brewster (Roddy McDowall), a writer penning a biography of Arlena that the actress tried to stop; Odell and Myra Gardener (James Mason and Sylvia Miles), theatrical producers who were financially shafted when Arlena refused to appear in a show; Arlena's husband, Kenneth (Denis Quilley); Kenneth's lover, Daphne (Maggie Smith); Patrick Redfern (Nicholas Clay), who was having an affair with Arlena; and Christine (Jane Birkin), Nicholas' wife. Ustinov would play Poirot again three years later in the made-for-TV feature Thirteen at Dinner.~ Mark Deming, All Movie Guide