1937年的洛山矶唐人街,警员杰克(杰克•尼科尔森 Jack Nicholson 饰)因不满这里的黑暗,辞职当起了私家侦探。这天,一个自称莫拉雷太太的女子请杰克调查丈夫的外遇,杰克欣然接受。杰克发现莫拉雷原来是当地水利总工程师,正在为兴建水坝问题和当地农民争执。随后有人给 了杰克一些证明莫拉雷偷情的照片,隔天早上真正的莫拉雷太太却找上门来要求杰克停止调查莫拉雷。 事情变得越来越迷离,杰克决心追查下去……JJ 'Jake' Gittes is a private detective who seems to specialize in matrimonial cases. He is hired by Evelyn Mulwray when she suspects her husband Hollis, builder of the city's water supply system, of having an affair. Gittes does what he does best and photographs him with a young girl but in the ensuing scandal, it seems he was hired by an impersonator and not the real Mrs. Mulwray. When Mr. Mulwray is found dead, Jake is plunged into a complex web of deceit involving murder, incest and municipal corruption all related to the city's water supply.