It is summer, and obsessed Ralf Gordon stalks a high-school teacher, 28-year-old Diane Marshall. He watches her from an old warehouse while she is relaxing in her swimsuit on one of the boats. One of Diane's students, 18-year-old Sean Roberts and Ralf's younger brother Lou, also watch her strip naked and exercise. An angry Ralf yells at them, brandishing a bayonet. Shocked at this, Lou falls over the railing to his death, for which Ralf falsely blames Sean. Later that night, Ralf confronts Sean again, threatening to cut the boy's tongue out should he reveal anything. The sheriff questions Sean, who lies due to seeing Ralf eyeing him. The next day, Sean meets with Diane, who invites him to have tea. Diane reveals that she knows about Ralf stalking her. On their way home, Sean and she see Ralf watching them. Diane invites Sean into her house for a drink. This soon escalates into a moment of passionate lovemaking while Ralf, unknown to them, watches jealously. Diane invites Sean to her boat the next day. Ralf arrives and threatens Sean with a handheld harpoon. However, upon seeing Diane, he flees. Diane later asks Sean to dinner, after which Ralf again threatens him with the bayonet. Diane then tells Sean's parents about Ralf's threats. The next day, Sean drives Diane home and they have a pool party together, then make love. Diane receives a phone call from her drifter husband telling her that he is coming back, but Diane tells him she is divorcing him. As Sean gets into his van to drive home, he is held at bayonet point by Ralf and ordered to drive to the warehouse. Sean manages to get away and arms himself with a rifle, but Ralf reveals that the gun is loaded with blanks. Ralf gets him in a chokehold, which ends up killing him. Diane arrives on the scene, where Ralf tells her that he killed Sean so he can be with her. A horrified Diane pleads tearfully with him. Ralf, overcome with anger and jealousy at Diane's love for Sean over himself, tries to strangle her. Diane manages to stab him with his own bayonet and flees crying, leaving Ralf to bleed to death. Diane finds Sean's body, breaks down and weeps.
Although 22 years old during principal production, North was still largely known to audiences as the impish child he had played 10 years before on the CBS family series Dennis the Menace. Prior to the release of the film, columnist Jack O'Brianreported of the "vulgarity" of North's first adult feature film role: "Nice little Jay North has a bang-up role in 'The Teacher' flick -- an explicit porn-scene with Angel Tompkins." While not impressed with what he deemed to be a "ludicrous" storyline, Los Angeles Times critic Kevin Thomas expressed appreciation for the portrayal of the film's two lead characters, writing:
The plot of 'The Teacher' isn't worth outlining, yet it develops a relationship between a 28-year-old woman and an 18-year-old high school boy with sensitivity and credibility unusual for an exploitation film. Avedis displays much concern for his people and allows Miss Tompkins and North plenty of room to give fresh, spontaneous performances.
