The following version of this book was used to create the guide: Highsmith, Patricia. Deep Water. W. W. Norton & Company, Inc., 2003.

Patricia Highsmith's psychological thriller, Deep Water, is set in Little Wesley, Massachusetts. The novel is written from the third person point of view and in the past tense. The following summary uses the present tense.

Vic Van Allen has a reputation for being a patient and long-suffering husband in his Little Wesley community. Although his wife Melinda is perpetually unfaithful, Vic never does anything to stop her affairs. Rather, he believes that Melinda has every right to her freedom and independence. He only wishes that Melinda would choose more intelligent and clever lovers.

One night at a party at his friend Horace Meller's house, Vic decides to take a different approach to his wife's philandering. During a conversation with her boyfriend, Joel Nash, Vic says that he is the man behind the unsolved Malcolm McRae murder. Malcolm was another of Melinda's lovers. Vic tells Joel that when he does not like how people interact with his wife, he kills them.

Terrified, Joel flees town. Vic is delighted, and soon retells the story to Melinda's next lover, Ralph Gosden. Ralph becomes similarly afraid, and distances himself from Melinda.

Word of Vic's story spreads through town. Vic delights in how the story only aids his reputation. People who know him think the tale is amusing and are glad that Vic is finally standing up for himself. Those who do not know Vic are suspicious of him, thus adding to Vic's mysterious aura.

When the McRae murder is finally solved, however, Vic feels deflated and weak. He misses the power and authority the story granted him. Therefore, when Melinda starts parading her new lover around at the Crowans' costume party, Vic's anger increases. After all of the other guests get out of the pool and reenter the house, Vic gets into the water with Charley. In a fit of impulsiveness and rage, Vic drowns Charley.

Everyone except Melinda thinks that Charley's death was an accident. They all dismiss Melinda's hysterical accusations, believing that she is only angry because she was sleeping with Charley.

After the coroner declares Charley's death an accident, Vic feels entirely peaceful and triumphant. Charley's death improves his mood and general regard for life. His outlook changes when he discovers Melinda has hired a detective with the help of the dour Don Wilson. Vic soon learns the name of the agency from which the detective was hired, and calls off his services.

Melinda starts seeing yet another man named Tony Cameron. Vic dislikes Tony immediately, but again does nothing to stop him. It is not until after Horace tells Vic that Melinda and Tony plan on running away together, that Vic realizes he must do away with Tony. He lures him into his car one afternoon and drives him to the abandoned quarry. Then he throws rocks at Tony's head until Tony stumbles and falls over the quarry's edge. At the bottom, Vic drags Tony into the water.

During a picnic at the quarry with Melinda not long later, Vic realizes in horror that Tony's body has resurfaced. The following day, he returns to the site to weigh the body back down. At the quarry's base, Vic is shocked to look up and see Don Wilson calling out to him. When Don joins Vic at the bottom, he immediately notices Tony's blood stains.

Back at the house, Vic hears Don and the cops arriving. Angry that he has lost, Vic strangles Melinda to death.