"Black Plumes" is a radio play adaptation of Margery Allingham's mystery novel. The plot revolves around the death of Robert Madrigal, the manager of a prestigious art gallery. He is found in the garden room with a gunshot wound1. His stepdaughter, Frances Ivory, who is engaged to David Field, an American painter, suspects that Robert's assistant, Henry Lucca, who was on an expedition with him in Tibet, may have something to do with it.

Frances also has to deal with her eccentric grandmother, who claims the gallery as her home, and her neurotic stepsister, who is married to Robert. The play follows the investigation of the police and the revelations of the characters' secrets and motives.