Lady Tressilian invites several guests to her seaside home for two weeks at the end of the summer. Tennis star Nevile Strange, former ward of Lady Tressilian's deceased husband, incurs her displeasure when he proposes (to her mind bizarrely) that both his new wife, Kay, and his former wife, Audrey, come at the same time. Lady Tressilian grudgingly agrees but events soon become sinister when she is brutally murdered in her bed!