A rich but disliked elderly man invites his relatives to a family reunion at his home. Once the gathering is complete, he announces enigmatically that he intends to change his will before he dies. Before he can do this, he is murdered. His niece (Gynt), a detective story writer, has to put her theories into practice by solving a real-life murder mystery.

Detective Inspector Campbell (Gordon Jackson) looks into the murder of a teacher at a girls school where there are a number of suspects, including her colleagues and the married man she had been seeing.