In a New York City apartment, a man is forced to simulate sex while lying facedown and naked in his bed while someone holds a gun to his head. As a recording of Phil Phillips’s “Sea Of Love” begins to play, the man is shot dead. The next day, alcoholic police detective Frank Keller pours orange juice for men who have “won” a breakfast with the New York Yankees. He takes the stage to inform the assembled men that the breakfast is a scam and they are all under arrest for outstanding warrants. Outside, Frank is accosted by a man and his young son bearing an “invitation” to the Yankees breakfast. Although the man is wanted for grand theft auto, Frank lets him go, preventing the little boy from witnessing his father being arrested. That night, Frank gets drunk and harasses his ex-wife, Denise, on the telephone. Across town, an elderly lady is fed up with her neighbor continuously playing “Sea of Love” and discovers the male victim dead in his bedroom. As they arrive at the crime scene, Frank is unable to hide his contempt for his partner, Gruber, who married Denise after their divorce. Inspecting the body, Frank theorizes that the victim was killed by a lover, insisting that people only play old records when are trying to impress a date. They receive a tip from the doorman that a television cable operator was in the building before the murder, so Frank goes to the cable company and questions Terry, a large, muscular repairman, who claims not to have seen anything. When a second man is killed in a similar manner, Frank is paired with Detective Sherman from another precinct. Sherman refers to the victim as a “Casanova” who sought out women by placing personal advertisements in the newspaper. After a drunken brawl with Gruber, Frank returns to the second victim’s apartment and passes out on the bed. Hearing the doorbell, he is greeted by a woman named Gina Gallagher, holding balloons, who has arrived in response to the victim’s ad in the New York Weekly. The next morning, a hung-over Frank discovers he and Sherman are working together because fingerprints at both crime scenes prove it was the same killer. Frank gets the idea to capture the killer by running his own dating advertisement, stating that the murderer responded to two of the three notices that included poetry. He explains they can take any women who answer the ad out for drinks to collect fingerprints. Sherman agrees, but suggests they first hunt down the third poet, Raymond Brown. They discover Brown is married with children, and has never followed through with any of the women who wrote him. The next day, however, Frank and Sherman find Brown dead in a hotel in the same position as the first two victims. The police detectives set up their sting operation in a restaurant, with Frank posing as the bachelor and Sherman disguised as a waiter. Several women arrive for a drink, and Sherman confiscates their glasses. Only one woman, Helen Cruger, leaves without touching her wine glass. The next day, Terry the cable man comes to precinct headquarters claiming he saw a black boy delivering groceries to the apartment house the day of the shooting. Frank hunts down the grocery store, only to discover it was a false lead. As Frank is buying fruit, he runs into Helen, who accuses him of plagiarizing his poem. He admits that his mother wrote the poem fifty years earlier to woo his father. Charmed, she accepts his invitation to a bar and later agrees to go back to his apartment. As she uses the bathroom, Frank glimpses a handgun in her purse. When she comes out, Frank defensively pushes her into the closet, but discovers the gun is only a starter pistol. Frank explains he panicked, and he and Helen make love. Once she leaves, Frank takes a coffee cup Helen touched and wraps it in plastic, but changes his mind. Later, Frank goes to the shoe store where Helen works as a manager. As they make another date, two young mobsters enter, and one of them identifies Frank as a cop. Frank apologizes for lying to Helen about his identity, and promises to be honest with her going forward. That night, Sherman plays the date role when Gina Gallagher arrives and recognizes Frank, who is playing the waiter. Frank explains what is going on, and Sherman and Gina share a drink. Later, Frank calls Helen to meet him at the grocery store wearing only a trench coat. After pretending not to know each other, Frank “picks her up,” and they go back to her place. Frank wakes up first and discovers Helen’s extensive record collection, including a copy of “Sea Of Love.” As she makes them drinks, Frank steals her social security card. Before he leaves, Helen shows him her sleeping daughter. At the police station, Frank runs Helen’s social security number to discover she does not have a criminal record. After another night of meeting suspects, Sherman announces he is too drunk to go home. Frank gives him the keys to his place before secretly meeting Helen at a fancy restaurant. As they walk back to her apartment, Frank accidentally reveals she was part of the sting operation. She curses Frank and runs off. After drowning his sorrows in alcohol, Frank stumbles back to Helen’s apartment, claiming he made up a story about the sting operation to push her away. He asks her to come home with him because he cannot sleep without her. She leaves to ask her mother to babysit, and Frank notices copies of the other three victims’ newspaper ads on the refrigerator with their names and telephone numbers. Helen returns, and tells him she needs time alone to think everything through. At home, Frank finds Sherman in bed with Gina Gallagher. After they leave, Helen stops by and plays his “Sea Of Love” record, remarking how she caught him admiring her copy. Frank accuses her of murder, but ultimately lets her go, aware that their fraternization would void any evidence he collected for the case. Helen bolts out the door, and a few moments later, the doorbell rings. When Frank answers, Terry the cable man attacks, revealing that he was once married to Helen and has been jealously stalking her and killing her new lovers. He forces Frank facedown on the bed and orders him to simulate sex. Frank grabs a trophy that has fallen on the floor and smashes it in Terry’s face, and the two men struggle for Terry’s gun until Frank pushes him out the window to his death. Weeks later, Frank joins Sherman at a bar, but only orders a club soda. Despondent about their estrangement, he begs Helen for another chance, and she invites him out for coffee.