A series of unsettling crank calls disrupts the isolated existence of Helen Clarvoe, propelling her into a dangerous web of extortion and violence. Helen, a wealthy and reclusive woman living in a modest hotel, finds her carefully controlled life unraveling when an acquaintance from her past begins a campaign of psychological harassment. As she attempts to navigate the threats, she is drawn into a criminal underworld involving pornography and vengeance. The narrative utilizes a third-person perspective to examine the deteriorating mental state of the protagonist as she faces forces beyond her experience.

Discussion often centers on Millar's ability to construct a claustrophobic atmosphere that reflects the internal state of her characters. Readers frequently highlight the precision of the prose and the way the author avoids traditional tropes in favor of a more clinical examination of madness. Critics often point to the book as a definitive example of the psychological thriller, noting the effectiveness of its slow-burn pacing. The narrative is widely praised for its sharp social commentary and the way it subverts expectations regarding the victim-villain dynamic. Many readers find the conclusion particularly impactful due to its logical yet unsettling resolution.