故事发生在1921年的英格兰,在一战中所经历的失败令压抑而又沉痛的气氛笼罩了在全国上下。弗洛伦斯(丽贝卡·豪尔 Rebecca Hall 饰)是一位打假义士,正义感极强的她将戳穿谎言揭露真相视为己任,她不相信世间有鬼魂存在,存在的只有险恶的人心。 在一所男子寄宿学校中,盛传着闹鬼的传闻,在人们口中,一个非正常死亡的男孩的鬼魂终日徘徊在校园中不肯离去。为了打消学生和家长的恐惧,学校委托弗洛伦斯前来调查。弗洛伦斯很快便展开了工作,在她的精明强干之下,事件的真相逐渐浮出了水面。而正当她以为问题已经得到了解决准备离开时,却发生了一件足以颠覆她此生全部信仰的事件。
Poirot pays what appears to be a routine visit to Dr. Morley, his dentist, but shortly after he leaves the clinic, the doctor is found dead with a gunshot wound to his temple, an apparent suicide. Poirot suspects foul play, and all those who entered the doctor's offices after Poirot left are suspect. They include Alaistair Blunt, a prominent and very influential bank director, Frank Carter, a young fascist thug with a personal grudge against Morley, Mr. Amberiotis, an enigmatic recent arrival from India suffering from a toothache, and Mabelle Sainsbury-Seale, a charity worker also recently returned from India. When Amberiotis is found dead in his hotel room from an overdose of Novocaine and Sainsbury-Seale disappears, Poirot rightly expands his list of suspects and connects the crime to events that occurred in India 12 years earlier.
When Tommy and Tuppence visit an elderly aunt in her nursing home, Tuppence is concerned by the odd behavior of some staff and residents. So when Tuppence hears about Aunt Ada's sudden death and the disappearance of her friend Mrs Lancaster, she realizes her concerns were right. Tuppence meets Miss Marple and together they follow a path of clues that lead them to the Norfolk village of Farrell St Edmund, where they find a community guarding an array of secrets. Only by getting to the bottom of these secrets do they begin to unravel the truth about the mystery of Aunt Ada's death and Mrs Lancaster's disappearance.