At the 1972 Washington State Chess Tournament, nine-year-old David Willerman and fourteen-year-old Peter Sanderson face each other in a match. When David loses, he attacks Peter, stabbing him with a pen. Later, David is sedated in a psychiatric hospital, and the doctor recommends he be kept from playing chess. In time, David’s father leaves him and his mentally unstable mother, who responds by slitting her wrists. When David finds her near death, he ignores her cries for help, and instead unlocks the drawer where his chessboard is hidden, and plays a game of chess. Twenty years later, Peter Sanderson returns to Roxbridge, Washington, to compete at the International Grandmasters Chess Tournament. He brings along his daughter, Erica, and his chess teacher, Jeremy Edmonds. Now a widower, Peter meets Debi Rutledge at the tournament, and later visits her home, where they have sex. After he leaves, a man claiming to be Peter buzzes Debi’s apartment saying he forgot something, but when she lets him in, the unseen man kills her. The next day, detectives Frank Sedman and Andy Wagner arrive to investigate. Debi’s wrist has been cut, and her body drained of blood. A neighbor reports hearing Debi having sex with someone the night before, and the detectives question Peter, but he denies seeing her that night. Sometime later, Peter receives an anonymous telephone call from the killer who wants to “play a game” with him, and references killing Debi. Later still, Peter receives a letter containing a photograph of her murdered body, and a message from the killer that he will receive another telephone call at 11:00 a.m. the following day. Peter reports the incident to Frank Sedman, admitting that he did know Debi, but was afraid that revealing so would interfere with his chess tournament. When Andy Wagner does not believe Peter’s story, Peter invites the detectives to listen in when the killer calls again. The detectives consult Doctor Fulton at the Roxbridge Institute of Psychology to create a profile of the killer. In time, psychology student Kathy Sheppard stages an “accidental” meeting with Peter in the hotel sauna, and asks about his experiences as a chess player. When she accidentally makes it clear that she knows who Peter is, he questions her identity and she quickly leaves. Kathy reports to Frank that she could not assess Peter in such a short time, and is surprised to learn that Peter is a suspect in a murder case. Kathy is angry that Frank and Doctor Fulton put her in a dangerous situation. Meanwhile, another woman is murdered in her home. Frank and Andy arrive at Peter’s hotel and wait for the killer’s phone call. When Kathy enters, Peter is surprised to learn she is a psychologist working with the detectives. The killer calls, and Peter asks why he murdered Debi Rutledge. The man tells Peter he was trying to get his attention, and that he has also committed a second murder. The killer vows to continue his killing spree if Peter refuses to play a “game” with him, and recites a riddle to hint at his next move. Despite the phone call, the detectives continue to suspect Peter is involved with the murders. Kathy visits Peter and chastises him for refusing to “play along” with the killer. Soon after, a third woman is killed. Kathy visits Peter in his hotel room, and warns that Andy Wagner thinks he is guilty, but she believes he is innocent. Before the killer’s next scheduled call, the detectives arrive and take Peter to the hotel basement where they can tap into the main phone line and trace the call. The murderer reveals he has chosen his next victim, and chastises Peter for missing the many clues he has left behind. In time, Kathy asks about Peter’s former wife and learns that she died years earlier in an automobile accident. When Kathy accuses Peter of being closed off, he becomes defensive. However, he confesses his growing feelings for Kathy, and kisses her. Afterward, they return to his hotel room and make love. While Peter showers, Kathy looks in the telephone book for the number of a restaurant, and is stunned to find that the names of the murdered women have been circled. As she gathers her things to leave, Peter explains that he was merely searching for a connection between the victims, and accuses Kathy of pretending to have feelings for him in order to investigate him. Sometime later, Peter plays an opponent at the chess tournament, and his coach, Jeremy Edmonds, is surprised when he misses an obvious move and loses the match. Jeremy accuses Peter of being distracted by Kathy Sheppard, but he denies it. The next day, a fourth victim is found, and Peter receives another phone call as Kathy and the detectives listen in. They try to decipher a note left by the killer, and Peter realizes the killer is using a map of Roxbridge as if it was a chessboard, and draws a grid over a map to determine where on the “board” the killer will make his next “move.” Peter asks his assistant, David, to research his past opponents who made similar “opening moves.” After guessing where the murderer will strike next, Frank sends an undercover officer to stand in for the tenant. Meanwhile, Peter plays in the chess tournament, but his match is postponed when the digital board malfunctions. While waiting for the anticipated attack, Frank learns that he may be in the wrong location, and travels across town to another site. He arrives too late and finds the body of another woman. Elsewhere, Peter visits Kathy to apologize, and admits she was right about him being emotionally closed off. After learning of the latest victim, Detective Andy Wagner accuses Peter of the murders. As the men engage in a fistfight, Peter’s wrist is cut, and the policeman points a gun at his head. Sometime later, Frank dismisses Kathy from the case after learning that she and Peter have become intimate. Before leaving, she insults the detectives for continuing to believe Peter is the killer without having any evidence against him. Soon after, the killer attacks Kathy in her house. As the masked man holds a knife to her throat, she notices that his wrist has been bandaged. Kathy fights her attacker, and runs for help. She tells Frank she now believes that Peter is indeed the killer after seeing the cut on the man’s wrist. However, Frank tells her that is not enough evidence to make an arrest. As Peter is at the chess tournament, Frank is called to the pier where the body of a drowned man has been discovered. The victim, Peter’s chess coach, Jeremy Edmonds, left a note on the railing stating, “Peter, I’m sorry, but I just can’t do it anymore.” Frank issues an arrest warrant for Peter Sanderson. After Frank and Andy find photographs of the murdered women hidden in Peter’s hotel room, they go to the tournament and arrest him. While in custody, Peter is given the phone number of an attorney, but when he calls, the killer answers and taunts him with another riddle. Elsewhere, Kathy researches the patient history at the psychiatric hospital to see if Peter was ever a patient there. Peter deciphers the killer’s message and tells detectives that his next move is to murder Peter’s daughter, Erica. Peter begs Frank to go the hotel and protect his daughter, promising to confess to the killings in order to solicit Frank’s help. Frank sends Andy Wagner to protect Erica, then transports Peter to a jail cell. However, Peter breaks free, steals an officer’s gun, and forces Frank and the officer into a cell before stealing a police car and driving to Erica’s rescue. Meanwhile, Kathy makes a discovery at the psychiatric hospital, and drives to the police station. Peter arrives at the hotel, but Erica is missing. He sees a note on a closet door saying “Check,” and finds Andy’s slain body inside. The telephone rings, and the killer taunts Peter, claiming to have his daughter. Peter realizes the killer is in the hotel basement, and races to save Erica. Once there, he discovers that the killer is his assistant, David. Peter sneaks up behind him and holds David at gunpoint. David reminds Peter that they played a chess match when they were children, and blames Peter for ruining his life by beating him. A fight ensues, and David beats Peter unconscious. Erica is tied in the corner and screams, as Frank and Kathy arrive. David attacks Frank and slits his throat. Kathy, who has learned David’s history from the records at the psychiatric hospital, tries to convince him that killing Erica will not bring back his dead mother. David regresses to his childhood, and confesses his guilt for letting his mother die. In a childlike voice, he explains that he took special care of his murder victims. As David moves toward Kathy with a knife, Peter revives and shoots him, pronouncing the game over.