汤尼(雷·米兰德 Ray Milland饰)和玛戈(格蕾丝·凯利 Grace Kelly 饰)是貌合神离的一对夫妻。汤尼常常为了他的事业和爱好,把娇妻忘在一边,二人感情亮出红灯。而生活寂寥的玛戈和作家马克不可避免的擦出爱之火花,他们约会、通信,不料竟被汤尼发现。汤尼没有 声张,只是写了一封匿名信给妻子以示警告。然而现在马克竟然造访家中,为了一雪耻辱,加之图谋得到妻子玛戈的丰厚财产,汤尼暗生毒计。 汤尼向旧时同学列斯开出了一千英镑的价钱,让其参与他布下的一整套严密杀人计划。这套计划有设计精妙的凶手不在场证据,电话、钥匙,窗帘,统统成为这个阴谋的道具设置。然而计划终究赶不上变化,列斯不但得不到赏金,还要赔上自己的性命。而汤尼却也急中生了智……In London, wealthy Margot Mary Wendice had a brief love affair with the American writer Mark Halliday while her husband and professional tennis player Tony Wendice was on a tennis tour. Tony quits playing to dedicate to his wife and finds a regular job. She decides to give him a second chance for their marriage. When Mark arrives from America to visit the couple, Margot tells him that she had destroyed all his letters but one that was stolen. Subsequently she was blackmailed, but she had never retrieved the stolen letter. Tony arrives home, claims that he needs to work and asks Margot to go with Mark to the theater. Meanwhile Tony calls Captain Lesgate (aka Charles Alexander Swann who studied with him at college) and blackmails him to murder his wife, so that he can inherit her fortune. But there is no perfect crime, and things do not work as planned.