They’re Playing with Fire

Diane, a literature professor, hires Jay Richard to varnish her yacht Lillian. During a break she seduces him and they begin an affair, blurring the lines between employer and student and pulling Jay into a dangerous plan.

Diane and her husband Michael hatch a scheme to use Jay to secure a large inheritance from Lillian and Lettie Stevens. They see Jay as a pawn who can trigger the relatives to leave or can prompt the fortune to shift in their favor.

The couple convinces Jay to frighten Michael's elderly relatives living in the house so they can move them to a retirement home. Jay agrees, hoping to keep the plan secret and avoid suspicion.

Jay's attempt to scare the relatives is interrupted by the family dog barking at him. Lillian pursues him and fires a rifle, forcing Jay to flee in fear as chaos erupts around the house.

Shortly after the failed scare, Lillian and Lettie Stevens are assassinated. The killings send shockwaves through the scheme and raise the stakes for everyone involved.

Jay runs to the boatyard and the news reaches Michael, who becomes suspicious of Jay. He phones Lillian and Lettie and learns they were murdered, pushing the plot toward suspicion and confrontation.

Michael accuses Jay of involvement, while Jay counters that Michael wants him as a scapegoat. Diane warns Jay not to go to the police, noting that Michael is capable of violence.

Cynthia, Jay's girlfriend, tries to blackmail him with photos of his affair with Diane. The killer, now dressed as Santa, murders her, revealing that the danger is far from over.

On campus, Diane observes Michael paying off George, who is Lillian's cousin. Michael accuses Diane of being the killer and conspiring with Jay; he ends their relationship.

Diane visits Jay and explains what has happened; they then begin to rekindle their relationship, sharing a tense but intimate moment.

Michael appears at the yacht; Diane and Jay escape there, with Jay admitting his love for Diane. Michael tracks them, briefly aims to shoot Jay, and the killer appears, killing Michael.

The killer, Martin, confronts them at the mansion. He is Huntington's chorea sufferer and the illegitimate child of George and Lettie, orchestrating the inheritance scheme. Martin kills George and later tries to kill Diane; Jay kills Martin, revealing him as Bird, a former school friend.

With the inheritance secured, Diane gifts Jay her car and invites him to Hawaii. They leave together, beginning a new life away from the web of deceit.