本片根据法国文豪莫泊桑的名著《奥尔拉》(法语:Le Horla)改编;主人公以第一人称的形式进行叙述。以日记形式描写了主人公的焦虑和恐慌:他感觉到有一个看不见的生物体存在于他的周围,并命名其为« 奥尔拉 »。 他开始还是清醒的,然后在试图摆脱奥尔拉无形的控制过程中,逐渐变得疯癫。Simon Cordier is a well-respected magistrate who visits a condemned prisoner, Louis Girot, just before the man's execution. Girot again pleads his innocence insisting that he has been taken over by a spirit that forced him to commit his crimes. Cordier doesn't believe him and the man suddenly dies. Cordier does however note a rapid change in his personality during their short interview. In the following days, Cordier must face a number of strange occurrences in his home. He begins to wonder if he is sleepwalking but is soon hearing voices and begins to wonder about his sanity. It's recommended to him that he take up sculpting, something he once had an interest in. He develops a relationship with Odette, a gold digger married to a struggling artist, but the evil, invisible spirit soon drives him to murder.