On Halloween night in a coastal New England town, thirteen-year-old Rynn Jacobs celebrates her birthday alone in the rented house she purportedly shares with her father, Lester, a poet. Rynn receives a visit from a neighbor, Frank Hallet, who enters the house uninvited. Newly arrived from England, Rynn and her father have leased the house from Frank’s mother, Cora Hallet, a real estate agent. When Frank inquires about Lester, Rynn claims he is in his study working and cannot be disturbed. Frank tells Rynn she is pretty and makes sexually suggestive comments before leaving. The following day, Rynn goes to the bank and cashes travelers checks. Later, Frank’s mother, Mrs. Hallet, drops in on Rynn and demands to see Lester, but Rynn claims her father is in New York City having lunch with his publisher. Mrs. Hallet asks if Frank has been to the house and cautions Rynn not to let him inside the next time. Mrs. Hallet thinks Rynn is rude and wonders why she is not in school; warning the girl that she is on the school board. Before leaving, Mrs. Hallet asks for some jelly jars that are stored in the cellar, but Rynn refuses to grant her access. The following day, Rynn takes the bus into town to learn the date of the next school board meeting. Afterward, she declines Frank’s offer of a ride home, but tells Frank that her father would like to speak with Mrs. Hallet. A police car pulls up and Frank retreats into a restaurant. Officer Ron Miglioriti asks Rynn if Frank was bothering her and escorts her home. After reporting that Lester is busy and cannot be disturbed, Rynn suggests to Officer Miglioriti that Frank is a pedophile and he confirms her theory. She buys two tickets for a police raffle and Miglioriti departs. A short time later, Mrs. Hallet returns and insists on seeing Rynn’s father, announcing the girl and her father must find other living arrangements, but Rynn argues that they have a three-year lease. She taunts the older woman about Frank’s predilection for young girls and Mrs Hallet slaps her. Rynn hands over the jelly jars and asks Mrs. Hallet to leave, but the woman insists the jars are useless without their rubber seals, so she lifts the trap door to the cellar to retrieve them. Downstairs, Mrs. Hallet screams and the door strikes her on the head, killing her. Rynn covers the trap door, tidies the house, and attempts to move Mrs. Hallet’s Bentley automobile, but it will not start. A teenage neighbor, Mario Podesta, rides his bicycle to a children’s birthday party, where he will perform as a magician, but stops with curiosity at seeing Rynn with Mrs. Hallet’s car. Mario, who has a prominent limp, tells Rynn that his father is a mechanic and owns a service station. Later that night, Mario returns and Rynn cooks him dinner in gratitude for taking the Bentley to Mrs. Hallet’s office. Mario explains that he is crippled because his parents lost track of which of their children had polio shots. In return for the confession, he wants to know why Rynn had him move the car, but she deflects his questions. Mario’s uncle, Officer Miglioriti, arrives to inform them that Frank has reported his mother missing. Mario protects Rynn, claiming that he met her father, Lester, that night, but he says that Lester retired for the evening. Satisfied, Officer Miglioriti leaves, warning the teens not to do anything he would not do. Shortly thereafter, Frank arrives and demands to see Rynn’s father. He grabs Rynn’s pet hamster and burns it with a cigarette before throwing it in the fireplace. Frank tries to intimidate Mario, but the boy wields a knife and chases Frank away. Rynn closes the curtains and leads Mario to the cellar. Afterward, he is shaken and wants to know long Rynn’s mother has been there. Rynn relates her story: she was living in England with her father when they found out he was dying. They came to the U.S. to keep Rynn away from her mother, making plans for Rynn’s well being after he was dead. Lester paid three years rent on the house and stocked a bank safe deposit box with travelers checks. He counseled her to make herself very small in the world to avoid notice. One Sunday night, he said goodbye and walked into the sea. He had studied the tides so that his body would never be found. A short time later, Rynn’s mother showed up at the house. Lester had given Rynn a white powder and said she was to put it in her mother’s tea if she ever resurfaced as it would calm her. After giving the potion to her mother, Rynn realized it was potassium cyanide, a poison with a bitter almond odor. When Rynn finishes the story, Mario tells her they should not speak on the telephone because someone might be listening. Days pass and Mario helps Rynn bury the bodies beside the house in the pouring rain. Mario is chilled and Rynn draws a bath for him. To help Mario get warm, Rynn climbs under a blanket with him in front of the fire. They make love and Mario goes home to have dinner with his family, with a promise to return. Later, Officer Miglioriti checks in on Rynn and tells her that he does not believe what she has been saying about her father. Rynn insists that he is upstairs, and Mario, wearing makeup, impersonates Lester, fooling his uncle. The following day, Officer Miglioriti returns, tells Rynn that Mario is in the hospital with pneumonia, and takes her to visit him. Realizing how much she needs Mario, Rynn understands that her father had been wrong about her ability to live on her own. Rynn eats dinner alone in a restaurant and returns home on the bus. After she goes to bed, she is awakened by the sound of the trapdoor slamming downstairs. Wearing Mario’s magician hat and cape, Frank emerges and confronts Rynn, explaining that he found a hairpin belonging to his mother and a red fingernail belonging to Rynn’s mother in the cellar. Frank insinuates that if Rynn becomes his lover, he will not reveal her secret and she can go on living as she has. Rynn serves Frank tea and cookies, but he is suspicious and asks that they switch cups. Rynn complies and he comments that the tea tastes like almonds. Rynn suggests that it must be the almond cookies and Frank begins to cough and choke as the poison takes effect.