Private investigator John Klute is hired to investigate the disappearance of a Pennsylvania executive named Tom Gruneman. His only lead is a series of obscene letters written by Gruneman to a New York City call girl named Bree Daniels. Klute travels to New York to interview Bree, who is initially uncooperative but later agrees to help him in exchange for his protection and a chance to escape her dangerous lifestyle. Bree, a complex and independent woman, soon becomes the focus of Klute's investigation as he navigates the dark, seedy underbelly of the city.

As Klute delves deeper into the case, he uncovers unsettling truths about the men who have been involved with Bree. The atmosphere grows tense as he pieces together clues that suggest a more sinister plot tied to Gruneman's disappearance. Throughout his investigation, Klute finds himself increasingly drawn to Bree, even as her life is threatened by a shadowy figure who constantly watches her. The suspense builds incrementally, drawing Klute and Bree into a web of intrigue and danger that challenges their trust in each other.