At a Bayonne, New Jersey, police station, Cynthia Kellogg meets with Detective John Woods and Detective Linda Nealon to give a statement about the death of James Urbanski, husband of her best friend, Joyce Urbanski. The Urbanski marriage had always been tempestuous. When asked if Joyce ever spoke of harming her husband, Cynthia recalls a particular afternoon: James Urbanski arrives at Joyce’s Clip ‘n’ Dye beauty salon to drop off his toddler son. Joyce is exasperated that her husband cannot watch their child. James admonishes his wife for missing a doctor’s appointment that morning. The two begin to yell at each other, until Joyce’s business partner, Cynthia, breaks up the argument. Before leaving the salon, the brutish James fills his pocket with money from the cash drawer. Cynthia comforts Joyce, who expresses a desire to kill her husband. A few years later, while on break at the salon, Joyce fills a sugar bowl with a mixture of rat poison and sugar. Cynthia watches her friend take the bowl upstairs to the Urbanski apartment. When Joyce returns to the salon, Cynthia dashes upstairs to distract James from using the sugar. She urges him to work on controlling his temper, provoking an emotional outburst from him. Just then, the phone rings, and Cynthia knocks over the sugar bowl while James is on the phone. Although he is upset, James turns his attention to Cynthia, insisting that she show him her breasts before leaving the apartment. Cynthia strikes him and runs back downstairs. Sometime later, Joyce picks up her best friend for a night on the town. Cynthia is disappointed to see James, high on cocaine, in the back seat of the van. The man insults Cynthia by making remarks about her husband, Arthur. When he begins flirting with Cynthia, Joyce swerves into oncoming traffic, accelerating toward a Mack truck. The crazed woman veers away at the last possible second, frightening Cynthia and thrilling James. They arrive at a carnival, and James asks Cynthia for money and drugs, before wandering away on his own. Later, he finds Joyce and asks for more money, which she does not have. An argument ensues, and Joyce throws the keys at the strung-out man, telling him to drive home. Cynthia follows James to the van, where he passes out. She shuts him into the back of the vehicle and returns to the carnival. A short while later, Joyce insists they leave. As they drive home, Cynthia realizes her friend is distraught and asks what happened. Joyce pulls over and reveals that she cut James’s throat with a box knife. Cynthia thinks they should call the police, but Joyce argues for covering up the murder. They dump the body over an embankment, and Cynthia throws the knife away. Later, the two women argue over their cover story. Cynthia, covered in blood, returns home and tells her husband about the evening’s events. He urges her to call police, but Cynthia fears incriminating her friend. Arthur agrees to support his wife, but in return, expects her to end her friendship with Joyce. The next day, Cynthia cleans out the back of the van and destroys the blood-spattered objects inside. When she returns the vehicle to the beauty salon, James’s brother, Joey, voices his suspicions about the events surrounding James’s death. At her husband’s wake, Joyce informs Cynthia that police have taken custody of the van. Joyce speaks rapidly and takes pills, before pleading with Cynthia to help her get rid of some of James’s personal belongings. Cynthia suggests they refrain from talking to each other for a while. Sometime later, Cynthia learns that Joyce, having cut her wrists, is being held in a women’s detention center. She visits her paranoid friend, and together, the two concoct a story about the van’s whereabouts the week of James’s murder. Cynthia offers to show investigators a “logbook” at the salon the next day. That night, Arthur confronts Cynthia when he finds a falsified appointment book among her belongings. He warns his wife to stay out of Joyce’s legal entanglements. Sometime later, Joyce knocks on Cynthia’s door and asks for James’s wallet, jewelry, and handgun. Arthur arrives home early and taunts Joyce about the investigation into her husband’s death. Cynthia escorts Joyce to the sidewalk, and the two women argue about Arthur’s knowledge of recent events. Although Cynthia defends her husband, she returns to find Arthur packing a suitcase and talking about hiring a divorce lawyer. The angry man threatens to turn Joyce in to authorities. A few evenings later, Cynthia takes her children to her parent’s house, where she receives a phone call from Joyce, who plans to go to the Kellogg house to confront Arthur. Cynthia does not take her friend seriously and falls asleep. Later, she returns to her home, where police inform her that Arthur has been killed. Just then, Detective Woods interrupts Cynthia, questioning several aspects of her story. Cynthia becomes defensive and leaves the interrogation room. The detective walks her to the front door, before calling Joyce Urbanski in for questioning. In her parked car, Cynthia reflects on the night at the carnival: After being yelled at by his wife, James stumbles to the van. Cynthia follows and urges him to get into the back of the vehicle, so he can sleep off his drunkenness. James pulls her inside and attempts to have sex with her. A struggle ensues. Cynthia grabs a box knife and cuts James’s throat. Distraught, she locates Joyce, who suggests taking the dying man to the hospital. However, Joyce realizes they could face charges, and decides it would be best to dump the body. Overcome by the memory of actual events, Cynthia returns to the police station, where she volunteers to amend her statement.